HOW: Begin in a seated position with a strap or a towel wrapped around the ball of your foot. While keeping the knee in a bent position pull your foot up towards you. You may need to choke up on the strap to get leverage with your arms.
FEEL: You will feel this stretch deep in the back of the calf or in the ankle.
COMPENSATION: Make sure when you pull, you are pulling the foot up towards your body. A common compensation is moving the knee when pulling the strap.