It seems crazy to me, to push through pain so bad it "makes you chest constrict", likely coming from bone as opposed to soft tissue, and in an area (foot) where long term damage would be very bad. I've pushed through minor cases of shin splints and tendonitis but what the author describes sounds irresponsible to me?
So I'm wondering if I'm too wimpy or if the author is irresponsible?
"When I rest I feel utterly lifeless except that my throat burns when I draw breath...I can scarcely go on. No despair, no happiness, no anxiety. I have not lost the mastery of my feelings, there are actually no more feelings. I consist only of will."
I've run ultras before and not long ago crossed the Alps on foot with nothing but a tent and good cheer.
The thing that would always make me stop is issues with slow-tissue (bones, joints etc). Not because "I feel this is the right think to do", but my body isn't leaving me any other choice. Ofc assuming the decision to stop or keep going isn't influenced by peer pressure.
I've once come home with bleeding nipples (chafed by a new white Asics running top) so badly that it looked like I had been shot on the trail and the bleeding wouldn't even stop in the shower. It was pain far worse than a sprained ankle or broken leg.
In your analogy I'd consider a sprained ankle "bad" pain while the chafed nips "good pain". Severity of pain might not be the most reliable indicator in mid-range pain levels. But it's always reliable when it dominates over a strong will. Basically you always know when you're _done_. Peer pressure is a dangerous cloud in judgement here which is why I hate doing these things competitively or with friends (one always ends up the sparing partner of the other).
Also "the wall" just means you didn't fuel correctly and now feel really tired/weak/etc. It completely sucks to be sure, but it's a "body" feeling, and not a "knee" or "hamstring" feeling at a specific part of your body.
Both may be true, but pushing though because it feels ok in the morning ala the author is crazy