Every day gets its own Org Mode file. What goes in is not specified, but things I’ve included so far include:

To do lists

Things I probably won’t do but would like to

Previous night’s dreams

Free-form journaling

Notes on projects in progress

Small snippets of beautiful code I’ve written or seen that day

Summary of the day’s events

Quotes or poems

The main thing is to write something every day and keep some kind of record about what’s happening in my life.

So far I’ve kept each day to a single page. At the end of the day, this page gets exported as a two-column PDF (via Org’s LaTeX export), printed out and kept in a binder on my desk. I review the binder occasionally to get a feel for how the days have been going.

If I continue on this path for a few more months, I’ll have a hundred or so entries; after a year, of course, hundreds. At that point I’ll probably concatentate the PDFs into a single PDF and turn it into a bound book, perhaps via Lulu.