He never dreamed he would finish his first marathon 14 days after he started it.
"I wanted to cry because I wasn't going to get to finish. I was so close to the finish line," McCord said.
At the time, McCord didn't know what had happened up ahead. His disappointment soon turned to disgust and fear after hearing of the bombings.
"It took me a couple of days before I could watch the coverage. It was too real."
Good can come from evil though. McCord says he's learned a lot from the experience and he shared his advice with excited Comanche students. They responded with handshakes, high-fives, and even gifts.
During his speech, McCord compared school to a marathon, both posing difficulties along the path to finishing.
"I ran in pouring rain. I ran in cold weather. Just a week before the marathon, I ran 18 miles in wind gusts of 45 mph," he said.
But, he never gave up and he encouraged the kids to do the same. Sophomore Alex Hinshaw wants to be a neurosurgeon someday and was inspired by McCord's words.
"Gotta stay in school and finish it because it's all worth it in the end," Hinshaw said.
Along with other eager students, Hinshaw jumped at the opportunity to run with McCord, joining him in completing the Boston Marathon.
But, they backed off as his run ended, and instead of being one of thousands to cross the finish line in Boston, all eyes were on David as he alone ran through the ribbon, a true hometown hero.
"It's like life coming back full circle, especially after the marathon. To be able to finish it here in Comanche, 1,700 miles away, with people that I love, and love me, means the world."
McCord wore the same shoes, shorts, and shirt he wore the day of the Boston Marathon.
He participated in the as a charity runner for his church, and raised $31,000. That's the third-highest amount of money out of 2,500 others runners doing the same.
One more reason his Boston experience will never be in vain.