Mental activities while reading
Before I get to my question, some background info about me: I have a difficult time concentrating, whether it's while reading, listening, or whatever. You could say that I have symptoms of AD(H)D, but without the hyperfocus. One thing I've found that helps while listening to podcasts, for example, is to engage in other activities at the same time that use other parts of the brain. A couple of examples that work for me are solving Sudokus and solving jigsaw puzzles. I know that a lot of other people find doodling helpful. All of these activities use different parts of the brain from listening.
However, none of these activities mentioned above work while reading--they all require the eyes, just as reading does. This leads to my question: Does anybody have any suggestions for activities that use other parts of the brain from reading, and that can be performed at the same time as reading? I know that some people do exercising (e.g., treadmill, stationary bike) while reading, but that doesn't really use that much of the rest of the brain; my mind would continue to wander to other areas while trying to read. (Plus, those types of exercise are borrrrrrrring, which means they wouldn't last very long for me. I don't own a car, so I get my exercise walking around town, but that requires paying attention to traffic, etc., so that's no good either.)
I know one option is to listen to audio books, as they require the same parts of the brain as podcasts, hence the same second activities (Sudokus, jigsaw puzzles, doodling) to activate the rest of the brain. However, most of the books I like to read (Star Trek) are not available in audio book format, especially not unabridged. So, even that's not totally an option.
So, like I asked before, does anybody have any ideas on what I (or anybody else in my situation) could do as a second activity to engage other parts of the brain while reading?