I used to do something similar. I would always travel with a book and read whenever my brain would idle or ruminate.

These days I make sure to download up about 4-5 interesting podcasts. Listening to really interesting topics and discussions keeps my mind fresh and engaged.

if my brain isnt stimulated 24/7 I tend to fall into a mental ocean of indifference, usually followed by complete emotional blankness. this is why I always stimulate myself, best for that is just listening to music, which is why I clock in, on average, 14 hours of music per day.

Cars and computers.

Cars and racing fascinate me because the engineering that goes into making a car handle well at high speed is insanely intricate. Plus track design can have a massive effect on a race. There’s just so much to think about and so many different cars and disciplines out there that it’s pretty much endless.

Similarly, computers have so much to learn about them. I could learn about them 24/7 my whole life and still not know everything about them. They’re a massive testament to human ingenuity and are such a core part of society, I’m glad I’m lucky enough to be alive at this point in technology.

Impellers are code for me. Someone asks me what I'm thinking. I can't remember 5 second ago. Impellers.

When I'm idle my brain also idles, though I don't have an inner monologue and can't internally visualise or whatever that is.

Sex. I'm hypersexual so that tends to be the default.

Not ADHD, just autistic. It used to be fantasizing of a successful career. Now it's just uncertainty about my rights (which affect it badly).