Changing your body means pushing your body. And no one knows how to do that better than the toughest CrossFit coaches in the game. We got the most devastatingly difficult (and impressively effective) workouts from Jay Adams, manager and head trainer at CrossFit Union Square in New York, and Justin Marcis, founder of Windy City Strength & Conditioning in Chicago. Each of the workouts are simple. But they sure aren’t easy.For Marcis' workouts, you'll need:KettlebellPlyo BoxPull-up BarAssault Bike or RowerFor Adams' workouts, you'll need:Pull-up BarKettlebellBarbell with WeightsFor each program, all modifications are in parentheses when they're needed.