I've had it. I'm still recovering from it. It's incredibly debilitating because it really just lays you up. I'd have to lie down after a basic light chore like washing the dishes or sweeping the floor. I spent ages going to doctors and specialists as and had every blood test under the sun.
Nothing physical turned up in any test. It was unbelievably frustrating to be constantly tired and sore with no apparent explanation. Finally a cause was found and this is what the experts said, that it was 15 years in the cult that frazzled my mind, which weakened my body.
Now I've been out for over a year but the damage is done. I'm recovering though, but not as fast as I like. Cfs sucks.