mind tuned to work during walk

Just went for a walk with the intention of relaxing my mind during a lunch break. Interesting thing though, as I am walking along, though I know I am looking at the path in front of me, I don't actually see it. Instead I see the CAD models of machine parts I am working on. So I'm out where the air feels nice, but I am still developing parts, trying to solve fit problems, still working. I know my eyes are open, and that there is light entering them, but it's like my brain is tuned to a different input.

I managed to not walk into any trees or trip over scurrying squirrels (by the way their activities along the olive tree path here at Cousteau are fascinating to watch), but probably only by dumb luck. It's really kinda freaky.