CFS is greatly misunderstood. It is MUCH MUCH more than being fatigued. The proper name is Myalgic Encephalomyletis. A normal person may fatigue easily, but after rest they are better. With CFS/ME after exertion you get very, very sick and it is hard to recover from. Normally building up exercise little by little makes you stronger bit by bit ... but with CFS/ME you can not do regular exercise or you will never recover.
The CDC has tried its hardest to make people think that it is a psychological issue or mental problem, and that is why Dr. Judy Mikovitz was one of the very few scientists doing serious research into it. These people are suffering greatly.

Chronic Fatigue Syndrome Caused by a Retrovirus similar to HIV / AIDS? -- Dr. Judy Mikovitz Medical Discovery as told in her book "PLAGUE"