To truly rock these body-contouring bottoms, you'll need to tackle every trouble spot from your waist down. This workout does just that, with 10 toners that sculpt your butt and legs while challenging your core and zapping excess jiggle too. "Doing supersets—pairs of exercises performed back-to-back—increases your heart rate, and resting between them brings it down," says Kimmel Yeager, specialty fitness director at the Pacific Sports Resort in San Diego, who created this program. "That technique—called metabolic training—burns more fat than working at a steady intensity." Start today and you'll be confidently shimmying into your favorite skinnies in just three weeks.
How it works: Three times a week, do every superset, in order, two times without stopping, resting for up to a minute before moving on to the next one. Do cardio on at least two other days.
You'll need: A pair of 5- to 10-pound dumbbells and a step or bench. (Beginners, skip the weights.)