I keep a daily journal. Beginning of day: Two things that I'm grateful for. End of day: Two things that went well that day, two things that could have gone better. Each "thing" is usually only a sentence or few long. I find that going back through the end-of-day sentences every so often is useful for doing 80-20 analyses to find out what seems to be bringing me the most happiness / dissatisfaction (at least as judged by my end-of-day assessments).