Great question.  Being fit and ready for snowboarding is very important.  It will help you have a lot more fun -- and that's what it's all about.  I stress full-body fitness.  Lower body for strength mainly and upper body to prevent injury and help in getting up!

Snowboarding is so different than anything that it really is impossible to condition all the parts of the body that will be getting worked, but you may want to try some of these exercises.

1) Jumping rope - Legs, ankles, shoulders, and cardio.
2) Squats - Legs and back.  Not too much weight!
3) Stretching - Stretch your quads, ankles, abs, torso (twisting), and hamstrings. Even wrists.  Gentle is fine - don't over-do it!
4) Simulated snowboarding - There is nothing like simulating the actual moves of snowboarding and the best ways to do that is to plop your board down on your living room carpet, don your boots and strap in to your ride.  Simulate the movements of carving, pivoting, falling, and getting up.

Try these out and let us know how it goes   HAVE FUN!

[Also, check out the article on Safety and Injuries here]

also wall sits!!!!!!! your thighs get a big workout on the mountain, build them up!

Good advise.  Thanks!

Another great Q&A,  I just wanted to add, gettin in the pool and treading water for @ 20 minutes lengthing the muscles, moving the legs and arms in different circular and up and down motions will really help, and if your gym has one a balance board will also help.