ADHD

Maybe my comment wasn't clear enough, I have a job that I find satisfying, teaching at a university. The five year job I had that forced repeatedly forced me off sick was as a health professional in a hospital, and it was very interesting, challenging and satisfying. But the repetition (not of the work with patients, which was endlessly varied) but just turning up at the same building every day, seeing the same collegues, keeping on top of paperwork, etc. was mentally exhausting.

The advantage to being a lecturer is that the commute, paperwork and stress is seasonal, so it doesn't just feel like an endless Sisyphian task. In a sense, it's less challenging and less satisfying work than my time in health (teaching a student something interesting isn't the same as saving someone's life!) but the work pattern works much better for me. I think that what the OP was describing about cyclical burnout might be something similar. There are lots of careers (many self employed) out there that are intensely busy for a block and then time off or starting a completely different project. When I start finding teaching too much (and I'm sure it'll happen eventually, but at least it's longer than a year!) I'll probably move into freelance coding or seasonal event management type stuff. Stuff where I can use my strengths of picking up stuff quickly and dealing with problems, but don't need to worry about the long haul.