My first manager at my first job, many years ago, gave me the very useful advice to "write down any task you spend more than fifteen minutes on". It doesn't have to be long, just enough to trigger your memory, or capture the relevant details.

This has consistently been incredibly useful; for my own recall, for quarterly and annual performance review time (easy to scan through and capture my "significant accomplishments") as well as every. single. time. a colleague asks "do you remember X years ago when we ...?"

I tend to break it down by month, with a bullet-point list of tasks. I've migrated from plain text files, to a wiki, to I don't remember what tool my employer at the time provided, to currently OneNote, with a Notebook for "work-tracking" and a page per month. I don't love OneNote, but it is automatically backed up in our corporate environment.

I like the idea of switching to VSCode, as I do most of my work in that, but need to figure out the best way to back it up.