Weighted seated twist (on stability ball)

Sit on a stability ball with your feet flat on the ground and your knees bent at a 90-degree angle. Hold a weight plate or dumbbell with both hands close to your chest. Engage your core and slowly rotate your torso to one side, keeping your hips stable. Pause for a moment at the end of the rotation, then slowly return to the starting position. Repeat the rotation to the other side. Continue alternating sides for the desired number of repetitions.