Ball Bridge Video
This exercise focuses on gluteal strength. Use a large stability ball - lie on your back with your shoulders and head supported on the ball and your feet flat on the floor, knees are bent 90 degrees. You will likely need to put your arms out to the side to help with balance. Lift your hips so that you're straight from your shoulders to your knees -- then slowly alternate lifting one foot at a time off the floor. Try to maintain a very stable position on the ball and hold the foot up for 3-5 seconds.