Your core consists of the collection of muscles around your midsection that, when strong enough, supports your body in almost everything it does.
Sit on the ball with your feet flat on the floor, then carefully lean back and roll yourself along the ball until it nests in the small of your back. Touch your hands lightly behind your ears and slowly lift your upper body off the ball, contracting your stomach muscles to their fullest. Hold for a second (longer as it gets easier), then lower back down and repeat.
Core benefit: Flat, firm abs
Lie on your left side. Bend your left arm so your forearm is extended in front of you as shown. Press into your left arm and lift your torso off the floor. Your upper body should form a straight line from your hips to your shoulders. Place your right hand on your hip. Hold 5 to 10 seconds. Lower to starting position. Complete a full set, then switch to the other side.
Core benefit: Svelte sides
Lie facedown on your stability ball so that your back is flat and your chest is off the ball. (If balance is a problem, you can anchor your feet against a wall.) Extend your arms straight in front of you toward the floor, palms facing up. Pull your shoulder blades in toward your spine and lift and extend your arms to the sides to create a T with your torso. Pause, then lower your body back to start.
Core benefit: Pretty posture
Lie on your back with hands behind your head and hook the ball with your legs so it's nestled between heels and hamstrings. Contract your abs and lift the ball off the floor, rolling your pelvis off the floor and tucking your knees toward your chest. Keep your navel pulled toward your spine throughout the move. Pause; then slowly lower your legs back to the starting position.
Core benefit: No more lower belly pooch
Stand with your arms extended, palms down. Tighten your abs and lift your right foot off the floor and slightly behind you. Bend forward and extend your right leg behind you until your upper body is parallel to the floor. Your body should form a T. Pause, then lower to the starting position. Alternate legs for a complete set to each side.
Core benefit: Improved balance and flexibility