Great idea to consider exercising! I think the type of exercise that you can tolerate and amount of time you are able to do it depends on how fit you are and if you stick with it will likely increase with time.

It wasn't easy in the beginning and some people say don't push yourself but I don't find much benefit in exercise if I'm not pushing myself. I have been blessed to be able to continue jogging, taking spin classes and the eliptical machine. I try to work-out at least 3 times a week and feel that it definitely helps with my mood and hopefully with my strength/stamina to fight this miserable disease.