Slowly lower into a lunge. Hold for a count, then bring your foot to the front, to starting position. During this exercise, be sure to watch your technique, says Henderson. "The number-one landmark to be wary of is your knee in relationship to your ankle. Keep the knee aligned directly over the ankle while performing squats, and the same for your front leg. If your knee goes past your shoe strings or blocks you from seeing your big toe, it’s gone too far."

Continue to lunge, alternating legs, until you've reached fifteen reps. Rest, and then do one or two more sets of fifteen, depending on your strength level — you'll end up with tight quads, hamstrings, and glutes.