HOW: Get into a comfortable position on a chair or bed with your foot elevated and supported on a surface so that your leg is straight and parallel to the ground. Place your foot into bag handles and place one handle above and below your knee. Place an item (2-5 lb.) into the bag. Let the weight of the bag pull your knee into extension for the time prescribed.
FEEL: This should feel like a stretch behind your knee, maybe even your calf and hamstring. It can be normal sometimes to feel discomfort in the front of the knee, try to readjust your position if it is not tolerable discomfort.