I was a competitive runner for many years and trained with some of the best. The difference between great runners and cyclists and everybody else is that they learn to tolerate pain - a lot of it - on a regular basis. They crave pain and can push their pain threshold far beyond what normal people would be able to tolerate. If you've ever seen a great runner working out - it's almost painful to even watch - but always…
They crave pain and can push their pain threshold... These two things seems contradictory. If they crave pain, why would they need to push their pain threshold? (Disclosure: I'm a wimpy athlete. I always thought pain was the body's signal that something was wrong, so I backed off. Your remark confuses me even more. Just trying to understand.)
For programmers/entrepreneurs, this may translate to pushing past your concentration/sleep/tenacity threshold.