If you can, keep a journal.

I haven't been doing a very good job lately of making entries, but given my memory has become so degraded, a few years ago I decided to start keeping a journal so I can try to remember my life a little better.

If I go back and read the entry, suddenly I'll remember that day. At least, part of it. Even though it's tedious, it's nice to be able to remember. Even if it's something as simple as "my family ate this for dinner, we watched a movie, it was pretty bad" you're still creating a log of that day for your older self to look back on and remember.