Do cardio on an incline to burn and firm. You'll work your hips and glutes. Plus, tackling a killer hill routine sculpts your legs and tones your behind.
Try these exercises: Jumping on a stepmill (that revolving staircase at the gym) or hitting the stairs -- they provide steeper climbs, the same as a 62 percent grade on a treadmill, Cedric Bryant, PhD, chief science officer for the American Council on Exercise says. "Even step-ups on a bench or taking a hilly hike will help."