I have CFS and only recently found out it’s caused by my UARS (upper airway resistance syndrome) - a disease similar to sleep apnea but occurs in seemingly young healthy people like me (have had it probably since high school). It’s due to having a narrow nasal airway and narrow airway in my throat due to having a small jaw that cannot fit my tongue in it. Luckily it can be fixed... with a lot of surgery (widening the jaw and then getting double jaw surgery to move both my jaws forward and out of my damn throat.

Could have been prevented when I was younger but my parents didn’t know about it / ignored recommendations from doctors when I was a child.

So, in some cases CFS is legit. I used to have so much energy, the only reason I do anything is because I have adderall to compensate for how tired I am.