Do this for every hobby you have as well, whether carpentry, learning Mandarin, or reading.

Keeping a record of your thoughts is so useful in establishing how you arrived at your current opinions. It helps you to make the mirror on yourself much clearer. I find it immensely useful to look at how I've approached problems and discover new insights from the patterns I can glean in my journals.

Plus it leaves behind a record of yourself in meat-space. Depending on the nature of the up-coming apocalypse this might come in handy.