Dumbbell one leg fly on exercise ball

Sit on an exercise ball with a dumbbell in each hand, palms facing each other. Place one foot on the ground and extend the other leg straight out in front of you. Lean forward slightly and bring your arms out to the sides, keeping a slight bend in your elbows. Slowly lower the dumbbells down and out to the sides, feeling a stretch in your chest. Pause for a moment at the bottom, then squeeze your chest muscles to bring the dumbbells back up to the starting position. Repeat for the desired number of repetitions, then switch legs and repeat.