Instructions:

1. Sit on an exercise ball with your feet flat on the ground and your back straight.
2. Hold a dumbbell in one hand with your palm facing up and your elbow bent at a 90-degree angle.
3. Extend your arm straight up towards the ceiling, keeping your elbow stationary.
4. Slowly lower the dumbbell back down to the starting position.
5. Repeat for the desired number of repetitions, then switch arms.