Not sure about second brain but I’ve come to the conclusion that a life long git repo is probably a good idea. eg keeping track of vaccines, medical history etc.
I keep is simple, three main section’s. A morning section where I write what I need to do that day, what happened already, what’s going on in my brain.
A evening section listing what I got done that day, and what’s going on in my brain.
The third section is technically the “first”. Which is a reflection on yesterday after a full night sleep. What I did wrong, what I need to improve on, etc.
A small section in which I include excerpts from my task lists for personal or work. A small section with generic daily goals like “For god sakes comment your code”.
Another small section I call “daily avoidance“ which is stuff I want to avoid, like “Working through lunch” basically bad habits, etc.
The reflection part I use as an outlet to write about what worked/didn’t work in achieving those goals, avoiding the bad habits or any other thoughts I had about yesterday or yesterdays work.
I keep both as strictly separate, I don’t write about work in the personal one unless it’s because I had a issue that caused a strong reaction. I.e Argument with co-worker. The work one doesn’t have personal stuff in it and is mostly talking about the projects or idea’s I had.
Most of them are less the 100 (average is less then 75) lines, with about 2 dozen or so markdown formatting.