Starting position: Stand tall with the balls of feet on the edge of a step, heels hanging over the edge, hold on to something for balance.
1. Lift one leg off the step. Lower the other heel towards the ground, as far as you can below the edge of the step. Keep the leg straight.
2. Lift the heel back up and keep pushing through the foot until you are standing on your toes.
3. Hold the top contraction for a couple of seconds.
4. Lower foot back to starting position.
Switch and repeat with the other foot.