There's a difference between being tired all the time - which I am, pretty much - and having this. After a couple of days' rest, I'm good for paddling a kayak around a marsh (which I did this past summer) for a couple of hours or walking a couple of miles through sand. A person with chronic fatigue syndrome would still be completely wrung out in that circumstance.

I know that in my case, it's partially the stress of being under multiple and sometimes conflicting deadlines, as well as being held responsible in situations over which I don't have much control.