THE TOWEL HAMSTRING
Lie flat on the floor. Stretch your legs in front of you and keep your arms at your sides.
Bend your right knee and rest your foot on the floor. Your knee and foot should be in a straight line down from your body; don’t let your knee drift to one side or the other. Bending your knee allows you to keep your hips planted firmly on the ground at all times.
Loop a towel under your left foot and grab the ends with both hands. Your leg should be only slightly bent at this point. Make sure the towel is long enough for you to get a good grip on it.
Pull on the towel to lift your leg off of the ground. Try to straighten your leg as much as possible as you continue lifting until it is at a 90 degree angle with the floor. Keep going until you feel a burn in your hamstring, then hold for 10 seconds.
Do the same with the other leg. Bend the left knee and place your left foot on the ground. Loop the towel around your right foot, then raise it with the towel.
Repeat 3 times with each leg, holding for 10 seconds each time.
As you become more flexible, you can choose to extend the knee on the leg that you are not stretching, ensuring both hips stay level with the ground.