I keep notes for a lot of things, but my philosophy with journal entries is "anything and everything + how I feel about it."
Sometimes it's about capturing moments. Other times it's about processing my shit, and just like getting it on the page and interrogating it. I'll frequently doodle a rough "mood compass" I've come up with to track where I'm at emotionally - but that's for more extreme moods (good and bad).
Sometimes I just feel like making marks and I'll just scratch out the alphabet or whatever nonsense comes to mind.
For me it often means sketching some silly stuff, just to empty my head and stop (over)thinking.
Yes, it's a form of self-care. It has a similar function to what I imagine meditation might. Like I go and close my door and make my marks (whatever they are that day) and usually feel much more "centered" after.
Don't know about the others but, like I mentioned in an earlier thread, I try to make (and often fail ;)) short daily entries (with a few info I want to keep a record of, like the time I woke up and my mood, and so on) but I will also write down the events of the day (nothing major, like politics or whatever drama is going on, just personal stuff, people I met,...) and various things I would like to be able to remember.
It's some effort but I also love when an entry contains a sketch. Even if I think it's awful in the moment, it's so nice to see it when I'm flipping back through pages - even the worst sketches really help capture a moment