I'm a software engineer, and I've been keeping a "lab journal" on and off for the past decade or so. A single markdown file per day, with the date as filename. First thing I do every day is copy the previous day's entry, give it a once over & remove what's no longer relevant. This helps me remember what I've been working on, and it's a track record of sorts.
There's a todo list at the top of each day's entry. But the rest is mostly free-form. Some days don't contain anything. Others contain meeting notes. Design ideas. Results of experiments. It's all plain text, so it's easily grep-able. Sometimes I look back at them to answer "why did I do that"-type questions. Sometimes $manager wonders what I've been working on or why it's taking so much time. I can just point at the journal and say "I've been doing 3 meetings every day and I've been onboarding people so I haven't had time to work on XYZ".
It's not much effort. And imho it's definitely worth it.
I do the same-ish thing. Main highlights on mine: 1) I start off the day with things I should be working on (samesies) 2) I use ### to demarcate different "working sessions" ... one for each meeting, etc. 3) I struggle with finding something that lets me: encrypt, search, big notes, and use multi platform easily :( Closest I've found was google keep so far .. but i hate relying on it like that. I'm pretty sure "something" plus encrypted sqlite will work once i find it. 4) I name it Today.YYYYMMDD ... I'm trying to get into the habit of retroing once a month, creating a Month.YYYYMMDD to try to be more reflective and understand high level impact I had and systemic issues I'm running into.
The number of times this has saved me time figuring out "Oh .. i saw that error before .. how did I fix it?" and "who did i talk to about X and what did they say" months to years later has proven to be super helpful and I will be continuing indefinitely.
There are many markdown based journal programs, some with encryption. Do these not work for you?
Can you suggest any in particular?