If there is anything that has helped me directly in building apps and do my day job, it is this - a consistent place to note down.
Something that is always available for you write or scribble.
What I use depends on the work I'm doing. I use a notebook and pen for day job which lies just beside my mouse on the table. It's always open - I make todos and do my thinking there.
When it comes to working on side projects, I use Notion as you can properly organize things there.
I don't need it for work as the tasks are already on a Jira board (or something similar) but for the side projects it's my job to organize.
Ideas pop up at weird times. Luckily I have my phone around and I quickly open Notion and add it to relevant board. I can organize it later when I'm at the computer.
I have my tasks as pages in a kanban board in Notion. When I'm working, I update the page. Not every task is small. Not every task can be complete in one go. So I keep updating the page.
This single thing has kept me productive I can say.
It also help me think better. Starting with code is not always best. I can write down ideas in the card or brainstorm in it. There are some tasks that need you to come up with words and sentences. Writing copy for your website, for example.
When you get some free time, you might not have the time to completely code that or even no access to a computer. You can just open the card on phone or iPad and make some progress.
This also makes it "not overwhelming" when you are at computer to do the work.
That's all I have. Do you write things down as well?