Nala,

There is an ergometer (ergometer is the scientific name for an exercise machine) that works arms only. It is like a bike, but the pedals are operated by the hands and not feet. I have seen it at my local 24 hour fitness.

There is also aquatherapy - if you look for a swimming pool, ask about aquatherapy in addition to swimming. People walk in water using floatation devices - even people who cannot walk on dry land; people also do resistance exercises in the water, so it counts as strength training. Finally, there are aquaaerobics classes. Most class participants are obese - you would not feel like an oddball there. And, there is aqua physical therapy that may be covered by insurance.