Start by getting into plank position with your forearms on the balance ball and your toes on the floor.
Keep your abs contracted, squeeze your glutes (the butt muscles), and keep your back straight—your body should form a straight line from your head to your feet.
Hold this position for the designated time amount, without sagging or arching at your hips.
To increase the difficulty, keep feet close together, or lift one foot off the floor. To decrease the difficulty, spread your feet wide apart for a larger base of support.
