attention

Long runs are where the hard problems come loose. The first hour belongs to the body; after that the mind is free to turn over whatever the desk could not resolve. Debugging works the same way: force rarely helps, distance does, and what surfaces is usually not the fix but the wrong assumption underneath it.

The cockpit teaches the stricter version. Fly the aeroplane first, and the right problem shows itself in the time that buys. Running offers the same time without the altitude, by removing every option except patience. Which here is not a virtue but a technique, and the one that separates a patch that works from an answer that is right.