Hold a pair of 5- to 15-pound dumbbells at hip level and stand facing a step with your right foot planted on the step. Leaning your chest forward slightly, lunge backward with your left leg, bending your right knee 90 degrees. From that position, bring your left foot up to meet the right on the step; squat and hold for 2 seconds. Stand and return to start. That's 1 rep. Repeat with the other leg; do 10 to 12 reps on each leg.