Get ready to blast your booty. "When done right, you're guaranteed a sore rear after a pistol day!" says 2014 Next Fitness Star Emily Schromm. "It's the best butt move." The crazy-cool squat variation works your core, quads, calves, and those glorious glutes.
Want to make it even harder? Remove the box. From a standing position, lift your leg, lower your body toward the floor, then return to start. Yowza!