Starting Position: Place a stability ball against a wall and gently lean against it, positioning the top of the ball into the small of your back, but making contact with your tailbone, low- and mid-back. Your feet should be positioned 6 - 12" out in front of your body, feet hip-width apart and facing forward or turned out slightly.
Depress and retract your scapulae (pull your shoulders down and back) without arching your low back and gently lean into the ball, while loading your weight through your heels. Place your hands on the front of your thighs.
Downward Phase: Inhale and slowly lower your body, rolling the ball down the wall simultaneously, but keeping contact with your tailbone, low and mid-back against the ball. Focus on dropping your hips under the ball and pushing your hips back to reduce potential stresses placed across your knees. Avoid any movement of your feet and keep your knees aligned over your 2nd toe. Continue to lower yourself until challenged or until your thighs align parallel to the floor and hold this position briefly.
Upward Phase: Exhale and slowly push your body up away from the floor, focusing on extending your hips to bring them back underneath your body. Continue pushing upwards until your hips and knees are fully extended.