Readers told us the original Warrior Workout is their favorite Men’s Health workout ever. So we asked Rachel Cosgrove, C.S.C.S.—the fat loss expert who created all the Warrior workout phases—to design an all-new version that's even more intense and effective. Like the original, this fourth phase requires only a pair of dumbbells, a stopwatch, and some serious grit. But try Cosgrove's plan just once, and you'll understand why it burns fat, sculpts muscle, and leads to fantastic results. Do this workout 3 days a week. Perform the exercises as a circuit, doing one movement after another. For each exercise, perform as many reps as you can in 40 seconds. Rest for 20 seconds as you transition to the next exercise. After you’ve done all 20 exercises, rest for 2 minutes. Repeat the entire circuit two more times.