Notes + Trello + timer/exercise.
I often bog myself down with thinking about too many things. I get new ideas (that immediately appear better) and drift into day dreams naturally.
What I started to do, since side project work for me is extremely limited (sometimes, only a single hour), I take a few minutes to brain dump every one-word thing I can think of that sums up what I'm working on. This is mindless and easy. Afterwards, I review the words and expand upon them to something actionable, which creates tasks. I then put those tasks into a trello board and get working. It's motivating to see the cards move across the flow and trello is good for minimal effort to move them along. This also gives me a place to pickup from if I need to stop for a while.
If I hit a wall or get curious about whether or not I'm doing something right/wrong, it immediately goes into a backlog on the notes and will be considered for the next round, not the current round.
Lastly, I turn on some music, either hard rock or cinematic type music and start a timer for 1 hour. Once the timer goes off, I get up and do a quick 10 push ups, reminding myself that time is passing and I too need to be moving along effectively.