HOW: Start in a long sitting position with a weight in your lap. Begin the exercise by lifting your feet off the ground and keeping your knees bent, abs tight, chest up. While holding the weight with both hands, you're going to move your upper body and lower body in the opposite directions and twist. Repeat in the opposite direction and repeat.
FEEL: This should feel like an ab and core workout.
COMPENSATION: Do not rush the movement and lose control, try to maintain optimal position with your trunk and low back. Slowly perform the twisting rotation to help with maintaining your balance.