If you think winter’s arrival limits you to the gym till spring, think again. There’s no better time to get outside and challenge yourself with these ultra-demanding snow sports. Try one, and you’ll not only slash calories and build muscle, but you’ll also enter a world of outdoor exercise that’s surprisingly accessible—and addicting. From riding half-pipe on a park board to powering up a mountain on snowshoes, here are the season’s severest snow sports. Adrenaline junkies, we present you the ultimate cold-weather rush.