1. Sit on the floor with your knees bent. Hold a weight (dumbbell or weight plate) straight out in front of your chest. Lean back so your torso is at a 45-degree angle to the floor and brace your core.
2. Without moving your torso, slowly (take 2 seconds) rotate your arms to one side as far as you possibly can. Pause for 3 seconds.
3. Slowly rotate your arms to the other side as far as you can. Pause again, then continue to alternate back and forth for the allotted time. A good goal is 30 seconds.