It’s a hard, simple calculus: Run until you can’t run anymore. Then run some more. Find a new source of energy and will. Then run even faster.
This reminded me of a time when Gary and I were running near the waterfront in downtown Portland. He said something along the lines of that when I get towards the top of a incline that I should push myself even harder. He had some explanation that involved how our bodies burn energy, use oxygen, etc... I don't recall the specifics.
Anyhow, a few years later, I recall this conversation each time I find myself overcoming the hardest part of a challenge. Below the surface... and a few layers below that, there is always more energy inside of me... yearning to be burned.