Have to disagree with most of the conclusions drawn in this thread, my cfs started acutely within the same week as experiencing very high stress and emotional load, my father found a reason to consider divorce which would have meant selling the house that I have lived at for approx 20 years, this was amplified by me having used to suffer quite a bit from OCD ( properly diagnosed etc ), and my personality in general. I used exercise to cope with the intense stress, contracted some sort of infection that initially seemed like a cold, then boom, and here we are...
Something that might interest Hip, I also had general anxiety disorder for a period of around 3 monthes,
in the same year that I developed CFS. When I had this chronic anxiety problem I felt that there were physiological changes to my body as a result, for example difficulty controlling temperature ( overheating / thirst ). I actually remember a short period where I felt very CFS like in terms of energy levels, difficulty walking anywhere, general feeling of the body etc, but missing most of the symptoms. I actually even did a diabetes self test not long after that, which reminds me of the noticable extent to how the body felt 'off'.
It was around a month after I started to feel normal again / control the anxiety that I got the CFS.