It all really depends on how badly you want to learn. My first season my arms felt like they were going to melt off my shoulders, from having to constantly push myself back up. Then my ankles would swell up from all the heel side slides and my toes were numb from all the toe side stands. I barely even made it back into the parking lot let alone drive home (thankfully I was there with a bunch of friends.). What did I do that next day? I got my ass back out and continued learning, because I fell in love w/ the sport.
Best suggestion I have for you is - Snowboarding takes a lot out of you, during off-season it's best if you start exercising (A LOT). I do 30 minute yoga (helps with balance), 30 minute core, and 30 min strength every day (no weekend breaks). Some good exercises are planks (core), pushups (arms), squats (for legs, you will NEED leg strength), and sissors (abs).
Lastly, don't be afraid to fall. The bruises are just there to serve as memory of the good days, as long as you don't end up in the hospital.