I'd like to try some gentle stretches and possibly very, very gentle strengthening exercises that don't involve standing or raising my arms (because of my orthostatic intolerance). I think yoga might be good for this. I'm interested in a book rather than a DVD because I can't play US DVDs on my UK DVD player and, having looked into this before, there don't seem to be any appropriate UK DVDs on this topic. I'm not well enough to attend a class. Any recommendations?