“When we look back at those days and weeks where not much happened — where it’s the same every day — not much is stored in memory and time feels [as though it has] passed very quickly,” says Marc Wittmann, a research fellow at the Institute for Frontier Areas in Psychology and Mental Health in Freiburg, Germany.
I’ve said something similar to people my age who complain that “the years flew by”.
You have to get out of the routine if you want to remember your life. If you went to the same office for forty years and did the same job, very little of those years will be in your memory.
I was lucky. I had a business where I went out to different businesses regularly. I have thousands of memories covering many years. My life did not “fly by”.
Nor does it fly by now. Writing every day helps. I don’t journal, but I am writing about different subjects and, because I’ve been doing that for many decades too, I know that I will remember writing them. I will have memories of these days. It is “flow” as your post mentions later.