Short answer: https://rtalbert.org/gtd/
(I'm not that guy. That's just my favorite resource on the topic.)
Long answer: Organizational system for tasks at work and in daily life. People think it sounds boring and makes your life too rigid, but I find it's exactly the opposite. Once I know what I need to get done and have it out of my head, it frees me up to (1) be deliberate about how I spend my time and (2) focus relatively distraction-free on whatever I'm doing at a given time, even if that's something simple like watching a movie without wondering whether there's something I forgot to do for work.
Everybody who is obsessed with an organizational system has their own version that worked for them -- for me, it was the one I linked above. The author's goal really resonated with me: be okay not doing what you're not doing. It's not always about doing more. It's about deciding what you need to do, doing that, and then not having to stress all the time. The article is tailored to academics, which was where I worked at the time, but I still use it now that I've moved on, and I see no reason it is not generally applicable.
It seems like a lot at first, but you don't do it all at once. Even the author of the article recommends that you start small. I spent years doing just the first few steps without even attempting bigger-picture planning and review stuff, and it was still life-changing for me.
If any of this resonates with you, I'd recommend you give the first step a shot today. Keep it simple, start small, but actually start.