To add to your point 1 - no particular mental focus also requires no audio input. It's so easy to fall into the habit of constantly having a podcast or an audiobook on.

Actually, audio and especially music can make it easier to go into a diffuse state. The trick is to make sure it's music without lyrics, or the volume is low enough you're not listening to the content of the talking.

Or, it's a song you've listened to a hundred times already and know the lyrics and the tempo by heart. At least, it works for me.

I can't confirm that, since as of late I've been getting great results with this:

https://www.youtube.com/watch?v=DydIK14AvXI

Of all places I thought I'd see that channel recommended, HN is close to last on the list. That guy puts up some really great stuff.

I originally found this channel searching for "Saturn noises". And Saturn noises I got.

Not sure how to interpret the "no audio input" part; for years, I've been able to get into this kind of flow simply by starting a minimalist, repetitive tune on a keyboard and let that run for an hour or longer. My most effective place for this is early morning events where the secret sauce is to avoid opening your eyes until the idea that is emerging is fully baked in your memory.

What’s wrong with music?

Nothing inherently wrong, but if your mind is thinking about the lyrics it might be hard to "wander". Of course varies from person to person

> Some kind of physical movement

My theory, unencumbered by evidence, is the movement shakes the thoughts around until they find a pattern where they fit together.

I always called this getting in the flow. A semi meditative state. I did long range cycling in my teens (100 miles or so) and this kicked off a pattern I still use today.

The Aristotelian “Peripatetic” school gets its name from the act of walking while philosophizing if my memory of undergrad philosophy still serves.

I throw my yoyo. Once you are good, your mind will wander.

This is a great idea, I bought into the yoyo fad as a kid in the 00s and still have the muscle memory for it, might try this out.

"Before enlightenment, chop wood, carry water. After enlightenment, chop wood, carry water."

There are some video games that also do it for me. Super Hexagon, One Finger Death Punch, Guitar Hero/Rock Band, Geometry Wars are the big ones.

These are all games that require some type of intense focus but where I surely begin making mistakes the moment I consciously think about my actions in the game. Sometimes this means getting in the zone and not thinking about anything at all, but sometimes my mind is instead allowed to wander it a way it doesn't normally, and without judgment.

Same happens when one learns touch typing using a tool where words are random or not valid words at all(like keybr).

When using such tool, at some point where there is no need to focus on keys or words, mind will drift into thinking something else.

> Some kind of physical movement

Much of our thought is based on metaphor of body movement.

A neuroscientist once said that our brain's primary purpose is to coordinate movement.