A promotion. A baby. Whatever the reason for falling off the workout wagon, it usually comes down to time. That's why this 20-minute workout trims and tightens in a flash—so you can get on with your life.
“Alternating between cardio and strength moves every minute keeps your body guessing and your heart rate elevated,” says Raphael Verela, creator of Circuit Works. “That results in a higher calorie burn than an ordinary strength or aerobic workout.” To melt even more fat, repeat the circuit a third time (for a 30-minute routine).