I have a Pilates chair that stays in the living room; I use it when I am watching a TV program (should probably use it as my computer chair since I'm on the Board enough!!). There's dozens of exercises that can be done with it, many which don't impact your joints. And, I swim at a local community center a few days a week. I've been told by many doctors and PTs that swimming is good overall for cardio and no impact on joints. They have a class where you do regular exercises in the water -- that was hard!!