Have worked with plenty of people like that in the past, energy levels (not wearing them out) and not making the muscles too sore is a HUGE concern to have. So very slow and very steady. They usually need more slow-go cardio if overweight and moderate weights, nothing too high reps either. Work on more strength...stay away from the glycolitic draining training as it wear them out.
Autoimmune disorders need alot of attention to diet. Google "leaky gut" and "autoimmune" disorders. I also did a whole post on Gut health
based alot on the premise of leaky gut. Many of my past clients saw good results once they started to clean up the diet, the ones that wouldn't clean up their diets....well I am sure are still having major issues.
Flare ups do happen....so you have to do your best to manage your workouts around them. It can be a longer road back to health for some people like this....especially if they are taking lots of medicine....but as long as they are making progress that is what counts.