Sit on a ball with your thigh parallel to the ground, your feet flat on the floor, and your back in a neutral position (slightly arched).
Activate your lower abdominals (transversus abdomini) by bringing your belly button inward and by activating your pelvic floor muscles 20 to 30% of a maximal contraction. Maintain steady abdominal breathing while you lift one foot off the floor and you bounce on the ball with your back in neutral position.