Targets: quads + glutes + hamstrings + calves + shoulders + core
Stand with legs hip-width apart, hands on your hips. Lunge forward into the 12:00 position with your right leg. Return to standing. Now, pretend you're the little hand on a clock, lunging forward at an angle to 1:30, out to 3:00, and backward to 4:30 and 6:00. Repeat with your left leg, moving in the opposite direction from 12:00 to 10:30, 9:00, 7:30, and 6:00. That's one set. Increase intensity by adding shoulder presses (with 5-pound dumbbells) to each lunge. By week four, progress to three sets with heavier weight, resting for 30 seconds in between. "Adding the shoulder press initiates your core by challenging your balance, says Keller.