OT: Snowboarding, picking it up in middle-age

You'll be fine for two days in a row.  I would suggest to get the most lessons you can at first.  If you're snowboarding, find a way to protect your tailbone.  Most people fall back to their butt a lot at first.  But also be aware that some people fall to their hands more and you may want to do something with your wrists, not sure what though, either an object or mindset to not overload your wrists while wiping out.

Bring or buy sunscreen if there is any sun peaking through at all.  The snow is white, and if the sky is bright, your face will be pink.

I go snowboarding to Tahoe every year but never been to Mammoth.

My advice to you is to have a group lesson or two. And, ditch the bunny hill after the lesson.  I'm an expert snowboarder and the hardest thing is actually something overly flat..too easy to catch an edge. The steeper the hill the better it is to learn...because easier to get on edge, and know it. To give you idea I'd be at Jackson Hole which is brutally hard and would make it down but the final run to the lift is very flattish and I wiped out a few times.  Bunny hills are no good for snowboarding.   So after lessons..go to the top and practice on your heel first. All the way down the mountain. It'll take you an hour.  Find the edge and learn slide effortlessly.  You gotta find that sweet spot where you can slide.   Then do the same but on other edge (toes).  Eventually you'll learn to switch.

I agree with those people who think you will end up hating life after a few days of snowboarding.  I tried exactly what you are proposing and failed miserably.  I was so beaten and bruised that I felt as if I'd been tortured by the KGB.

I went back to skiing (which I have been doing since LBJ was president).  

Days 1-3 on a snowboard SUCK. Sore butt, really sore forearms, tired legs. Falling a lot but if you are used to that way of riding from skateboarding/surfing, after day 2 or 3 it should click and you can hold your own. At least that’s what happens for me. 
 

I started snowboarding at age ~22 and didn’t grow up skiing so might’ve been easier to pick up thank someone that had to forget how to ski. One thing I found easier when learning was to go on real runs and not stay on the bunny hill. It’s harder to snowboard on a flatter run than a regular trail. 

id recommend a group lesson the first day or first half day and then figure it out from there. Once you get your legs under you and know the basics then a private lesson might make more sense 

as a 40+ yr old now, stretch before, stretch after, hell stretch during (esp forearms!). And take a nice long soak after the day is done - you’ll have earned it. 

Based on your self description, I've probably got a body cast at the medical center you can use afterward.  You can stop by before your trip to make sure it fits, in case you don't die.

How bout golf?

Hit ball, get in cart, hit ball again.  Repeat for 17 more holes. 

No bruising or soreness.  

Ski, don’t board 

I’m a lifelong skier

With the shape skies now, skiing is easier to learn AND easier to master.  There is more to master as you get good at it.  And cooler. 

Beginning snowboarding means you will end up on your ass a lot and at the end of the day your ass and back will be sore.  With skiing your muscles will be sore but thats it. 

With skiing, it’s far easier to get around than on a snowboard.  Easier walking to the lift, traversing to anywhere, and getting on and off a lift.  

Definitely take a lesson before you go.  Skip all group lessons, you will be wasting your time and will be standing around waiting a lot for all your fellow beginners to pick themselves back up off the slopes from all the falls. 
 

As a beginner, expect to only ski a half day.  Ideally get a private lesson each half day.  With a private lesson you will learn 10x as fast.  They can skip any intermediate steps. There is a lot of technique in skiing, so lessons are critical. Some technique is counterintuitive.  You will need to learn to first comfortably control your speed and safely stop.  Then you’ll learn to parallel stop, get on and off a lift, parallel turn, get back up on your own on a slope and put your skis back on, and finally do it all on a slightly steeper slope.  If you know how to skate, that will help you learn how to skate across a flat traverse to the lift.  If you can learn that all before you go you might be able to go on your own the second day.  I don’t recall how fast an adult can learn.  I taught my kids at 3 and 4  and it’s definitely not that fast.  Whatever you do, make sure you first learn to control your speed and stop…for your safety and others.  I remember an out of control, self taught, 20 year old beginning boarder crashing into my 4 year old on the beginner run.  My 4 year old was in great control on his first day out.  It was as horrible as it sounds.  

You won’t be acclimated for the altitude at Mammoth or the muscles you need to use.  It takes three days of skiing before you are acclimated. I do sprints up steps.  Not the fake steps in a gym that move for you but real steps like the stadium.  Work your way up to ten sets of 50 - 100 steps or similar.  I do this so that my first days aren’t wasted.  Even if you are an expert skier you can’t ski if you are winded after two turns.  With such a short trip, any conditioning ahead of time makes a big difference and you’ll have more fun. With the right conditioning you could ski all day. 

Don’t expect to ski with your buddies. It’s not happening unless they are also beginners.  Since you are thinking about boarding I assume they might be boarders.  That’s often what determines what people choose.  My kids and their friends all ski.  

Make sure you save some energy to enjoy the apres ski with your buddies.  There will be fun places to meet at the end of the day and some fun places (you might need to lift it up and down) on the mountain.  A beer never tastes better than after a hard day of skiing.

Fear is your only enemy.  Don’t lean back. 

You only live once, go for it. 

Reiterating some of the things the snowboarders mentioned (skiiers always seems to be against boarders, no offense meant all!)

Absolutely do the bunny and even a private lesson or at least have a friend who boards help. I snowboarded once in undergrad then picked it up again a few years ago, I'm 34 now. 

My advice is do the bunny hill and instruction the first day to get your idea of balance and how to fall. Then move on the to the bunny slope to get an idea of picking up speed and balance. But after 1.5 days, you will have to move to a green to get the speed necessary to really get the feeling of the edge catching the snow that you don't get on the bunny. Practice a lot on going from toe to heel, then heel to toe (which feels scarier because you're turning away from the slope) and learned how to stop/plow snow.

My friend gave me the advice to go 3 days in a row to really get the feeling locked in at least for this trip. You will likely only be able to endure about 4 hours a day while your feet and body do get beat up. You skateboarded so try to remember how to fall, keep your arms in to not hurt a shoulder and not land on your wrists.

Last bit of advice if you are able to start consistently go down greens is if you think to yourself "I can do one more run" STOP. Famous last words. Almost all of my injuries and my friends I juries both skiing and snowboarding is when they said they could do one more run.

Have fun and if mammoth has good snow, you won't hurt AS bad. 

As a note, I don't try to shred but I like to coast once you are able to learn how to go front to back side and vice versa because this is also how you pick up speed which is more important for snowboarding to continue to move than skiing.

Also, my opinion, snowboarding is still much cooler than skiing ha

Probably late to the game here but I agree with those who said to opt for skiing. The wife and I, both in our 40s, tried downhill for the first time last year and had a blast. We got group  lessons, which I recommend, but were fortunate that we were the only first timers so we basically got individual attention.

I too skated a lot in my teens to my early 20s and one of my friends had warned me about snowboarding because you can't bail when you are about to fall. I took his advice and was thankful watching beginner snowboarders wipeout a lot. Downhill skiing is a ton of fun and I don't see the need for the unnecessary frustration of a steep learning curve at our age.

I learned at age 42.  It isn't that bad.  I took a 3 hour lesson and just pulled the band aid immediately.  It is tough at first but I love it and went last weekend.  I prefer it to skiing by far.  The boots are so comfy wandering around when you aren't actually on the board.  You are going to eat shit the first couple days and it will feel helpless but you will get it.

I loved snowboarding. I had to give it up after neck surgery in 2011, but if I could still do it I would ride every chance I could.

I snowboarded for 15 years (probably only went 40 times).   Sitting down and strapping in and out every run  sucks. Crashing sucks. Even with a helmet you hit your head and your tailbone and your wrists a lot. Even after I was decent enough that I could do most any slope the strapping in was still really annoying.  I started skiing 8-9 years ago when my kids were old enough to hit the slopes.  I taught myself and was skiing down most of the hills by the end of the day. I almost never crash. I just pop on and off the lift without having to stop. The only bad part of skiing is all of the snowboarders blocking the path. 

Snowboarding is a lot of fun, but it sort of sucks.  Skiing is far superior.  ...and you can do it when you're old.

I tried to learn to snowboard when I was around 26, after a trip or two I gave up and switched to skiing. Getting to the point where you are having fun is waaaayyy easier on skis than snowboard. One caveat that I'll add tho is that I've never been described as nimble or coordinated.

From what I remember, when snowboarding when I fell it was almost always because I caught an edge and fell forward, often in quite a violent manner. Even in my mid-20s I could hardly walk after a day of getting the wind knocked out of me.

With skiing, when I fall its almost always on my butt and in more of a sliding manner. The impact isn't nearly as violent. 

Another thing to keep in mind is your mobility. When snowboarding you have one foot locked in and one foot free. For short trips you are often faster than skiers who don't have the free foot to help with mobility. For longer trips, or uphill trips, the skier will just unclip and walk, while totally unclipping from a snowboard is much more difficult.

I'm a bit older than you and have been boarding since I was 12.  I've helped many friends over the years and some of the following tips have been pretty useful for most.  Keep your center of gravity low while you figure it out initially.  Also, many here have mentioned falling on your butt a lot, which will happen. You also have to be really careful when you fall for forward.  Your instinct will be to catch your fall with your hands.  Wrist injuries often occur as a result of repeated forward falls.  This is why you need to stay low. You can use your knees and hands to soften the fall.  If you find yourself suddenly catching a lot of speed, purposefully go down until you are comfortable controlling yourself.  There's nothing like "catching an edge" at a high rate of speed when you're learning.  This experience alone is enough to make many quit.  

I got back into skiing in my late 40s after a 20 year break.  I'm enjoying it and ski the black diamonds but I don't push myself to the point of falling.  I don't think my joints could handle that and I don't have any desire to try snowboarding for that reason.  I personally would recommend skiing but if you're starting from scratch, it might not make that much of a difference.

Ski. It’ll take less time to have fun doing it. You can only take so many days of a 7 year old blowing by you on the slopes. 

I've been snowboarding since 1986, and I'm completely self taught.

My wife switched from skiing to snowboarding in 2000, and took lessons.

1) Definitely take a lesson. Hard to say whether you'll need more than one. My wife did not.

2) How sore? Hard to say - but it could be bad. I recommend wrist guards and hip/butt pads (they make riding the lift nicer also).

3) To get competent, skiing and snowboarding are about equally difficult... but there is really no intermediate step like snowplowing with skiis - so getting to the point where you can get down the slope a bit as a beginner is harder with a snowboard,

Yes to both multiple days of lessons and private lessons, if you can afford them. Group lessons are a mixed bag IME. If small, then you'll probably get enough individual attention and that'll be great. If they're bigger (say, more than four people), the instructor is going to be spreading feedback out too much or focused too much on the weakest link to give you a lot of feedback. (Unless, of course, you are the weakest link.) You'll be overwhelmed the first day, a lesson the second day is an opportunity to consolidate what you learned the day before. If you're patient and pay attention, you should make big strides from one day to the next.

You'll be sore but not so sore that you can't get out of bed the next day. Soreness goes away for the most part with warming up, anyway.

Biggest advice is be patient and practice what you learn in the lesson, outside the lesson, even if you feel like you could go faster. Unless you think this is going to be a one-off and you're never gonna snowboard again, in which case: bombs away.

My $.02. 
 

i learned to snow board in my early 20s and did it for  20 years before switching to skiing 2 years ago. 
 

if you can afford it, I highly recommend private lessons. Much, much more effective for beginners. Group lessons suffer from least common denominator problem. There will be one or two people who suck so bad that half your time will be spent waiting for them. Private lessons ensure you get the attention you need as a beginner and will get you up and riding faster so you can enjoy the trip more. 
 

regarding skiing or snowboarding, they are both great activities and have become a bit of an obsession for me. I find snowboarding to be more meditative for me. I’m one with the board, my movements are all about fluidity, and I leave the mountain feeling like my mind is clear. Skiing is more like golf, in that I have to focus on body mechanics and is a discipline that I will never stop trying to perfect. At my age, 47, I switched to skiing mainly because I find it easier to enjoy with others, especially my kids.  You fall less, you don’t have to unstrap and slowly kick your way through flats, chairlifts are faster and easier, it opens up more terrain, etc.  if it was a perfect powder day and it was just me, I’d dust off my board and head to my favorite mountain for the day. If I’m with friends or family and conditions are more variable, I’m pulling out my skis and having a blast. Either way, I hope you enjoy  it as much as i have. Have fun! 

I transitioned from skiing to snowboarding in my 50s . . .  it can be done. The problem with skiing for some people (like me) is that ski boots are really uncomfortable--so much so that it pretty much killed the joy. In contrast, snowboard boots are so much nicer and I can pretty much snowboard for hours without even loosening the laces.

All the advice you've gotten in here is good. I'll just add a couple of things: 

1) Buy these and wear them: https://www.amazon.com/Hillbilly-protective-gear-2704-Pad-Impact/dp/B002UHXY8G. I know they look stupid (do these make my ass look large? Yes!) but they will absolutely keep you from destroying your coccyx, which is one of the major injuries suffered by beginners. 

2) Practice balancing with your front foot strapped in and your back foot just sitting on the board . . . that's how you'll exit a lift and not falling every single time you disembark will make your day a lot more fun.

3) Unlike skiing, be conservative about increasing the difficulty level as you improve. Jumping into slopes much steeper than you're able to navigate will probably lead to excess speed and spectacular, painful falls. If the only way you can descend the mountain is by skidding on your heels, the run is too hard for you. You're not really snowboarding and you're ruining the snow for everyone else. It's much more fun to carve gentle linked turns on a bunny hill than skid your way down a steep run too terrified to make a turn.

Off topic, but I recently bought a pair of roller skates. We used to be at Skateland a lot of Saturdays on the Eastside.

The best way to prepare for a ski/snowboarding trip is to go into a walk-in freezer, sit on a block of ice and burn $100 dollar bills.

The best way to relieve wrist and arm sprains from snowboarding can be found in a shot glass at the bar. I speak from experience. 

Day 2 is the day you get it. Enjoy.

I began snowboarding in my early 40's too (6' 170/lbs).  But I was an expert skier and I even raced NCSA in college.  I did it because my girlfriend at the time snowboarded and sometimes I was bored with skiing.  To begin with it's completely different from skiing.  If you don't have a friend to teach you, a private or semi-private lesson or two will be beneficial.  Too much standing around with a group lesson.  I wasn't sore at all when I was learning but I was sweating the whole time and I was tired after 1/2 day so after lunch I would ski for the rest of the day.  Be careful, because when you fall, you typically fall forward and you put your hand out to stop you. Broken wrists are common in snowboarding.  After I learned to snowboard I realized I like skiing so much better...

I match your description and I learned at age 40. My 6 year old son and I took a private one hour lesson from a teenage girl at our local Michigan ski hill (Alpine). After that one hour we went out on the hills and we never looked back. Take a private lesson at a local small hill before going to mammoth. 
 

I didn’t fall that much but it was enough to hurt my tailbone that first day. I’ve heard some good advice: wear hockey pants to pad your butt and tailbone).