I don't know how many hundreds of times I've heard it said in the LDS Church: "Keep a journal!"
The huge problem here -- that practice rarely works.
That's because we are victims of habit and only writing in a journal occasionally means one of two things: you either never write in it, or your rarely write in it.
Even when you do write in it, it is usually so far after some event or experience that you can't recall all the details.
Do what I've done for more than 40 years -- keep a diary.
Now I don't mean those pocket size store bought diaries. I mean a full looseleaf size tablet or binder.
Write in it every day and you miss nothing. Some days it might be a few lines, others many lines or a half page or so.
That way it becomes a habit and your actually do it, like brushing your teeth -- I write in my diary/journal (what it really is) 99 percent of the time on that exact day. The other 1 percent I still catch up and thus it captures 100 percent of my life.
If I want to know what happened 10, 20, 30 or even 40 years ago, I can find it in my diary/journal.
My handwriting was gotten worse over the years, but besides leaving accounts of my good and bad experiences in life for posterity, writing it down helps me cope with adversity better and helps me know where I've been.
These diary/journals have also settled arguments over events over the years and even fill in gaps in my memory.
If I re-read most entries, even those 40 years ago, the accounts usually help me recall that exact day.
I don't have a photographic mind, but these diary/journals do spark and enhance what memory I do have.
So, try it, or you'll leave what my Great-Aunt Iris left my mother, a 200 page "journal" with just two pages written on-- because there was no established habit for her to keep writing in it.
All those blank pages .....