And again, we seem to have a similar view on things :D
Trail running is more fun and very different than running on roads. Running on roads is like meditation, first my mind wanders around being busy thinking for about 20-30 minutes. Then, it "declutters" (no idea how to explain that) and my feet are just doing their thing and my head feels clear. Beautiful experience and necessary to balance my days in the lab.
Trail running is very different. I am hyper-aware, jumping around, adapting to ever changing terrain, changing speeds, constantly going up and down. For some reason it feels more natural to me than road running. It taps into a similar place like rock climbing does, to me. As if it is rooted in a place deeper in my brain and it feels "right" doing it.