I've run several half-marathons. They've all gone differently, but I've noticed similar patterns. They usually start out with a feeling of dread (only 60 words, wide-open grid; shudder), knowing that I'll be in for some pain. Not sure what kind, but there's sure to be some sort.
When the horn sounds, there's such a mass of people that you can barely move (my first pass through the clues, I filled in only one square). But when you cross the starting line and start picking up momentum, what a feeling of relief (OMG, so glad to have randomly known the MONSTER logo!).
And the first two miles? What a rush as you get into your rhythm (AMERICANA and SPEAKEASY crossing SAY PLEASE, awesome!). Even feeling decently good as you hit mile three and four (ANTICRIME … not bad).
Then come the first pangs (PACA). Whether a knee twinge or having that first sense that you might have to drop a sewer pickle (TREN), it's not good. You push right through though, and it's worth it because you have the satisfaction (SOMBREROS!) that you made it through the first twitches.
The halfway point brings a dread that you still have miles to go, and wait, what's hurting now? (That LALO / PEALE crossing, oof.) Another mile in, strange sensations erupt all over (EL MARIACHI, what? Who says TABLET PC? What's the CALDER CUP?). And then more flood through you(EMPANELS?).
But you fight, because you know there's going to be a few last highs (TEA TASTER, LA SCALA) before the finish.
Then, everything begins to sear and burn as the final mile approaches (ANSE? ALFIO who? STET. BAAL?). But that finish line is in sight. Your legs have a strange leadlike quality (TRADES IN, ARE NOT) that you have to ignore. And when the crowd starts roaring near mile marker 13 (SLAM POETS!), that's all the rush you need to bring it home.
About two hours (39:33, about 3x my usual Saturday time) filled with mixed, powerful emotions, and you come away with the awesome sense that you finished something daunting. You've earned a well-deserved rest after the intense workout.
Now, where's my "I Finished the Kevin Der 60-word Crossword" shirt?