Exercising with chronic disability a big problem and one that I share. I agree with Wuzzle, better to peddle for 4 min. and congratulate yourself than to strive for more, then stop altogether because it precipitates more problems. Also agree that exercise has many guises...tense/release, leg raises while sitting at computer, deep breathing, and maybe the most important...the mental exercise of celebrating all that you have going for you. In many cases staying in the same place (rather than slipping down) is a huge achievement. Not as exciting as breaking thru that ribbon, maybe, but a hell of a lot better than the alternative.