I suppose I've been around a lot longer than most on here.
I started keeping a journal in 1969. Wish I had begun it earlier. Not a diary in which you write every day. A journal you only write in when you feel like it; to note events that are important to you. My journals have entries about my personal feelings at the time, my work, my hunting and fishing trips; just all sorts of things. I started using military record books, and now use 3 ring binders that are 3 inches thick. Pages are in plastic page protectors. I am now on volume 21.
I keep my journals with all my family history stuff. One day my kids will get it, or if they don't want it they are instructed to give it all to the local historical society.