I have weak knees to begin with and always do knee exercises daily. Now I strive to meditate 20 minutes in morning, 20 minutes at night. I like Burmese position because it feels like my hips are stretching. However it strains my knees (my right knee in particular), so I have to lie down a few minutes before getting up again. Google shows that all sitting on floor positions can injure knee. Only sitting on chair is good for people with bad knees. But I want to meditate while sitting on floor. How to do this without straining knees?