I endorse this. I go to yoga, and I just miss out the bits that my joints can't cope with. I give everything a go the first time, gently and not too much, then if I find I haven't got a problem I do it a bit more the next time, and I've been surprised at what I can do. Yoga is also really good exercise - it gives you a great workout (some of it while you're lying down!) and uses every part of the body.