Missed this last comment until now, but that only works if most/all of your work is code related. I started this habit as I was transitioning from individual contributor/team lead to CTO. Since the git log approach did not work anymore (there were quite a few days where I myself didn't code at all) I started doing the text file as a way to record other things (PM, planning meetings, client relations, 1-on-1 meetings etc).
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