One habit that I really appreciate picking up early in life is taking a lot of notes.
The format doesn’t matter as long as it’s something you can search or index, so I don’t recommend paper. (I still like taking notes on paper, but see them as more transient.)
One thing I didn’t appreciate was going to happen is the ability to talk to your notes. My computer has access to over a decade’s worth of ideas, thoughts and dreams. I can ask it questions about it, or highlight themes from my thinking from a period of time. I find it extraordinary valuable. It’s like having a conversation with your past self.
I think over time these archives of our thoughts become the best artifact of who we are. Reading books is the closest we’ve got to time travel. Maybe our notes are the best artifact of who we are we can leave behind?