I've always liked the idea of keeping a journal, but my life is too mundane and repetitive to keep a detailed log of daily happenings, so I gave myself the goal of writing something down every time a new, interesting, fresh thought strikes me. That's one of my criteria. I also write stuff down if I'm at some new territory, emotion-wise, and I need to document the intensity of that emotional state. I don't make writing in it a chore; my entries are spaced irregularly. I've gone months without writing, then written for three days straight, then abandoned the journal for a few days, and written a sentence. It all depends on how life's going and the track my mind follows during a given time period. I find that I make most of my entries at odd hours in the nighttime (when most of my most interesting thoughts occur, lol).