Come to a seated position on an exercise mat with your back straight and chest lifted. Place both your legs in front of you, with your knees bent and feet firmly on the floor. Your feet should be wider than hip width. Place a wall ball directly behind you and take a wide grip of a dowel stick or PVC pipe (or equivalent). Lie back and use the wall ball as a back support. Keeping your glutes on the floor, extend your arms up and overhead, letting your upper back arch over the top of the wall ball. Your arms should finish up and behind you, maintaining that extended position. Hold for the recommended amount of time.