The more senior your job title, the more you need to keep a journal (2017)
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.