Standing on either a 6” to 8” box, or the bottom stair of a staircase, face backwards to the edge and balance on the balls of your feet, hands on hips, so heels are in mid-air. Rise up onto your toes (both feet), then SLOWLY lower the right heel down as far as you can comfortably go (allow the opposite knee to bend), then with a smooth exhale, raise back up onto your toes. Repeat with left heel; that is one rep. Do as many reps as possible in the time allotted.