Snowboarding and skiing are incredibly demanding physically. To be able to ride even the gentlest groomers all day your legs need to be absolutely bullet proof. Your legs are your shock absorbers, being in a constant, varying degree of a squat all day really takes its toll. The only way to be able to shred all week is to do some leg training before you get to the mountains.   I am a Canadian Association of Snowboard Instructors level 2 coach, not quite a T-Rice or Shaun White