Place the top of your left foot on the ball. Keep your right knee soft — do not lock your standing knee.
Reach your arms forward at shoulder height. If balancing in this position is too challenging, open your arms out to the sides. Inhale to prepare.
Exhale, and actively pull your deep abs toward your spine. Bend your right knee, engage your right glute, and lunge. The ball will move back, and your shin will move to the top of the ball. Make sure your right knee doesn't move beyond your toes.
Inhale to straighten your front leg. This completes one repetition.