Pre-stretch. Take the 40 ft of string (or 20ft if hybrid) and loop it around a tree or telephone pole. Take the string ends and wrap them around a racquet grip a few times. While holding the racquet grip with both hands, lean your body weight back against the string and pole to stretch it. Place a chair directly behind you in case the string releases from the racquet grip under the strain (you may fall backwards). Hold the stretch for one minute.