I am on one of my rare fitness phases at the moment. I have recently lost around a stone and want to add a bit of exercise into my daily routine. The problem is, I have a lot of trouble with my back. Even long walk can leave me in pain. I know that swimming is a good option, but I have no car at the moment and the swimming pool is miles away. Can anyone suggest exercises that I can do at home that will help me get fitter without harming my back? I can't really afford to buy any equipment either.