From a recent article in The New Yorker, What We Think About When We Run:
"Golf rounds are slow and baseball games borderline endless, but the actual moments of play are comparatively brief and highly focused; like faster, reflex-reliant sports—basketball, soccer, ice hockey—they do not conduce to abstract thinking. In endurance running, by contrast, one thinks at great length while doing the activity. To run five or ten or twenty-six miles is, as much as anything else, to engage in a sustained way with the deep strangeness that is the human mind.
. . . Confronted with difficulty of any kind—a throbbing ankle, a stitch in the side, cold, hunger, headwinds, loneliness, despair, boredom, grief—runners will inevitably talk about 'running through it.' In its more modest connotation, the phrase simply means to keep going. But the grander meaning is that 'through it' means 'past it.' That is the runner’s great article of faith: that a better mood will supplant a worse one, pain will ease up, joy will kick in."