All my life I've done this weird mental bookmarking thing. I'll be sitting watching TV or on the toilet or something and be thinking absently about the future. Like, "I can't imagine having a baby. That would be so scary. But I bet I'll do it one day." or, "Right now I think boys are really stupid and awful, but when I become a teenager, all that is going to change and I will have no control over it". Then I decide that when those times come, I'm going to think of those moments where I was younger and thinking those things, to keep showing myself that things change rapidly, and to remember more innocent times. It's worked too. When I had Wolf, I thought of my 12 year old self fearing childbirth. At my first teeenage crush, I did think of myself at 8, and laughed.
Bookmarks in my brain of the past. It might be slightly neurotic. Like just now on the toilet, thinking to myself "Some day, I'm going to be incredibly elderly, should I survive that long, and I'll spend half my life in a toilet cubicle." And when that day comes, I'm going to remember today.