This is really, really good.
Few grammatical mistakes:
"I remind myself of all my running; that fear cannot stop me from at least running that three mile race every Thursday afternoon"... since you put a semi-colon, take out "that".
Consider deleting "This ran through my mind everyday" (ahh, intentional pun?) and just put "I constantly remind myself that all my running has been for something; fear is enough to stop me from running that three mile race every Thursday afternoon."
Coach Mack would always say "mind over matter."
Quipping in Coach Mack here is a bit awkward. Ii know you're trying to bring back the "mind over matter" thing, but this part is a bit redundant. Consider revising.
Overall, I like your rendition of the athletic/sports essay, because most people would write about how they lost in a huge race, but realized that winning isn't all that important, and blahblah (highly overdone. I'm glad you didn't do this).