I need some help and suggestions please

Hello, quickly I would like to explain some of my physical issues. I have a form of MD that is called Charcot-Marie-Tooth. Well because of it I have atrophying of muscles in my legs (more my left then the right) and in my hands and arms. Because of this I can't do a full body work out and it has to be broken down into upper and lower workouts that are about 20 minutes long.

I do use a stationary bike for about 80 (4 ~ 20 minute sessions) and that works with my legs, but my problem is that I am kind of at a lost as to what to do with my upper body. I try to do some crunches but that is not really enough. I have tried to search online for upper body workouts that dont require having to stand but haven't found anything. Do you guys know of a site that might be a start to look? Almost any site would be helpful for maybe I could make things work.

Thank you for your help.