There are many mild forms of exercise that you can engage in to keep yourself reasonably toned when you can't do more strenuous activities. Like the previous posters mentioned, yoga and walking are excellent. Also Pilates, especially if you take a few private lessons and tell the teacher before you start about your physical limitations. If you belong to a gym, invest in a couple of sessions with a personal trainer--when you book your appointment mention your physical problems so s/he can design a program specifically for you. And don't ignore exercise DVDs--there are some specifically for people with arthritis and fibromyalgia that might be perfect for you.