I think you have had some great replies here. My only thought is one from my neurologist who is also a physiologist. He really recommends "breaks". So that may mean in the short term you goon a stationary bike for 10 mins, take a break for 5; then go at it again. I find pushing through it makes things worse for me. I'm still working so sometimes I can't avoid that. But when I feel the fatigue coming on I just stop. Sit on the couch, take a nap if it is really bad. And I try not to overdo on the good days.