Stability-Ball Bent-Over Rear-Delt Fly
Sit on top of a stability ball with your feet and legs together, and hold a set of dumbbells with your palms facing inward. Hinge forward from your hips with a flat back so your torso rests on top of your thighs and the weights are resting on the floor with your arms straight. Bend your elbows slightly, then lift the weights up and to the sides until they come about level with your torso, then slowly lower to the start.