Lie flat on your back with your knees bent(placing your knees on the floor or resting on a bench). Place your left hand over your left ear. Roll your upper body up to the right until your left elbow touches your right knee. Concentrate on tensing the sides of your waist and holding contraction throughout the movement. Slowly lower to the starting position. After completing a full set of reps on the left side,switch to your right side and do the same thing.