This question was harder to answer than I thought it would be. What DO I do on long runs?

I do try to vary where I run when it's going to be more than 12 miles for several weeks (months) in a row.

I also have an endurance coping technique, which is to say "I'm ALREADY 10% done!" even though that's only 1-2 miles Crossing 50% done is a huge mental win, and then major landmarks similarly if I'm running on a course (things like starting the second loop, etc). Your typical "break it down into pieces" stuff.

I visualize, especially crossing finish lines (trust me, visualizing an Ironman or even marathon finish never gets old), or where I'd be in this course or that course ("the aid station with the ford inspiration station" "going over the big hill, glad I'm not doing that right now").

Mantras. I've done it before, I'll do it again. Light and fast. Bring it on, I can take you. Depends on the weather and how I'm feeling.

Lately I've taken my dog with me, but that will come to an end as seasons change and I increase mileage. It feels good to do something for her, and I try to take things in with her on another level.

I do think about stuff, or I'll "write" in my head (how would I describe this run, this thing I passed, my experience in general).

From what I have read, you can break your long run into 2 long runs in the same day and still benefit (increase your endurance). If you can't do over 2 hours but you have 4 hours to run, do 2 hours in the morning, eat some breakfast/lunch, then do 2 more hours. You have to account for the increased warm-up time of two runs instead of one, but still get your miles in. Come race day, there will be a lot of distractions as it is.