Cable one arm fly on exercise ball

Sit on an exercise ball with your feet flat on the ground and your back straight. Hold a cable handle in one hand and extend your arm out to the side, parallel to the ground. Keep your elbow slightly bent and your palm facing forward. Slowly bring your arm across your body, squeezing your chest muscles. Pause for a moment at the end of the movement, then slowly return to the starting position. Repeat for the desired number of repetitions, then switch sides.