For this exercise, sit on your mat resting on your tailbone, with your knees slightly bent and your feet flat on the floor. Lean back, with your elbows bent and forearms slightly raised, and make a loose fist with each arm, holding them at chest level.
Begin rotating your body right to left and back, in an easy rocking motion. This exercise is not about speed, but rather range of motion. Do not twist so far that it hurts, but try to increase your reach each time you do the exercise. If you would like to make this exercise a bit more challenging, lean back and raise your feet slightly off the ground.
This forces your core muscles to work harder to maintain your balance, burning more calories and making the motion more difficult.