Hmmm... pacing yourself might be a better idea. (As if you didn’t know that... *\;-)
I used to do that, before I ever got sick. I had to because of my back. Now, I wish it was “just” my back.
http://www.cfids.org/about-cfids/symptoms.asp
Go here. This makes it sound pretty benign, but trust me: I’ve always been active and athletic. I’m now a poster child for CFIDS.