Stand with your knees soft and feet slightly less than shoulder-width apart. Grasp a medicine ball by its sides. With arms extended and elbows slightly bent (maintain this position throughout the exercise), raise the ball to sternum level.

Keeping your head facing forwards, swing the medicine ball to the right by rotating at the waist. Make sure you keep your hips fixed. Continue the rotation until the ball is at the side of your body. Aggressively contract the oblique muscles on the right side to prevent the ball from going behind the body and repeat the movement in the opposite direction.

Added difficulty: Perform the rotation while kneeling down with your knees together. Increase the weight and size of the medicine ball as you become stronger.