Dumbbell one arm chest fly on exercise ball

Sit on an exercise ball with a dumbbell in one hand and your feet flat on the ground. Walk your feet forward, rolling the ball until your upper back is supported on the ball and your head, neck, and shoulders are off the ball. Extend your arm with the dumbbell straight up above your chest, palm facing inward. Slowly lower the dumbbell out to the side, keeping a slight bend in your elbow. Pause for a moment when your arm is parallel to the ground. Engage your chest muscles to bring the dumbbell back up to the starting position. Repeat for the desired number of repetitions, then switch arms.