It is alot easier to learn backtension with less let off than 80%. It helps to physically know what muscles are involved in the process. I learned by shooting traditional bows with fingers (snap shooting doesn't count). If you have access to a lower weight recurve (35 to 40lb.) you can draw it back and hold it until you feel the burn in your back muscles. Saves you from the humiliating experience of punching yourself in the face.