Begin lying on your back with your knees bent and feet flat on the floor
Lift one leg off the ground so the thigh is vertical, and knee is bent. Grasp the leg behind your thigh.
Straighten the knee as much as possible while maintaining a vertical thigh, pointing your toes towards the ceiling as your straighten the knee.
Then, bend the knee to return to the starting position. Bend your ankle towards you as you bend the knee on the return.
Repeat as prescribed.