Here is a sequence of stretches that one can do on the floor. They follow eachother smoothly and stretch each leg very nicely. Goodbye knee and back pain!
Be patient these are short animations and they may take a while to load.
1. Touch your toes (no picture; just sit and touch your toes).
2. Cross right leg and push your knee down
3. Pull left knee up, push seat forward.
4. Drop left knee, squish right knee down.
5. Straighten left leg, twist and push right knee to left with left elbow.
6. Un-cross legs, push right knee back.
7. Hurdler's stretch, lie front, lie back.
Hold each for about 25", repeat for other leg.
Making all these was a great learning experience in Adobe Photoshop.