I've not been a fan of audio books, but I've gotten addicted to listening to lectures and interviews on YouTube. (Especially to fall asleep to.) It started with me wanting to learn the context of world affairs, like the war in Ukraine. These sources provide way, way better information than watching the news on TV. I discovered that our broadcast and cable news is all highly filtered, but that's a whole other subject. These alternative sources of info give me real food for thought, but I guess it is still a passive activity. I need to get back to sitting with a book once in a while. My reading now is all stuff that I Google, which is mostly "skimming" for quick answers. Besides the stronger mental engagement of book reading, which I think your doctor is correct about, I would add writing as a good workout for the mind, particularly if you're writing in an interactive venue like these forums. Therapists used to encourage me to journal, which I found boring and not helpful to my mental health. I couldn't get into it. Doing it, I felt I had no focus. It was just pointless mental meandering. Participating in these MSF threads feels much more like I'm using my brain. A year ago, I started contributing to the "Comments" section that follow YouTube videos. That sometimes leads to interaction that is stimulating. It's also encourages being concise. Lengthy comments get ignored. People aren't there to read essays. Both there and here, I try to study what elicits a response.

I heard that doing math actually improves how the brain is wired. I'm not good at math, but when school forced me to do math exercises, it did make me feel better mentally. Working math problems is like calisthenics for the mind. I wonder if mathematicians have a lower incidence of cognitive impairment when they age.

At least with audio books, you can be doing something else while you listen. Sitting in front of a television screen puts you in a state of passivity that I'm sure can't be good for the brain. It's the ultimate passive activity. You sit motionless and just stare and listen.

Well, I think I'll iron in front of the TV. I've done enough sitting today.