During my 10 years with CFS I have been able to weight lift during this time. Anaerobic exercise is high intensity for short duration. It's easy to determine when you have done enough and not overdo it. Physically I appear to be in very good shape and look like someone who regularly visits the gym. Recently I have had to travel and had a week away from the gym and seen that my symptoms have improved substantially. I was noticing recently that my brain fog seemed to be tied to lunch or the workout just prior perhaps. I know now it's my exercising. I'm not sure what is happening, I think it might be tied to gut bugs. I also get increased anxiety and moody which disappeared when I stopped those 2 separate weeks. I suspect most brain fog or mental issues associated with CFS are probably due to the gut. Any ideas?