Last year I started reading Meditations by Marcus Aurelius. While I was reading it, I was struck at how many of the entries were just simple reminders to himself. Don't get mad at people unnecessarily. Remember that you are just one of many. Don't get distracted.
He was making the same mistakes over and over, just like I was.
I thought that writing down what I learned would help it stick. Every time I wanted to add a new tidbit, I would review all of them. It worked much better than I thought it would: it brought issues to the forefront of my mind that I wasn't considering. This was especially helpful when I was in a rush or under stress. [...]
This reminds me a lot of Dale Carnegie's "How to Stop Worrying and Start Living".
In the first chapter he talks about how successful people often sit once or twice a week and write down the mistakes they made in order that they might make them less in the future.