Every couple of months or so, I quit photography for good. "That's it," I tell my wife, "I'm done. This whole photography thing was fun while it lasted, but it's going nowhere and I can't stand it any longer."
My last printing session a couple of years ago was a nightmare; I think my biggest mistake was trying to attempt 10-hour sessions in a temporary (bathroom) darkroom with not enough ventilation. None of those prints turned out.