At the Boston Marathon on Monday, thousands of determined people ran across the finish line on Boylston Street. But one resilient man didn't run across — he crawled. His name is Micah Herndon, and he is a Marine veteran who told himself he would do anything to finish the race.

Herndon told CBS Boston his legs locked near mile 22. The Ohioan, who served in Afghanistan, fell to the ground. Others might have given up and waited for medical assistance, but Herndon started crawling.

He wasn't in the race for himself, he was doing it to honor three Marine comrades who died in a bombing attack overseas. He has their names tattooed on his hand, and they gave him strength during the marathon.

Herndon has his three friends' names tattooed on his hand. He repeated them to himself to get through the race. CBS Boston

"I say their last names out loud while I'm listening to my music," Herndon told CBS Boston. "I just repeat: 'Ballard, Hamer, Juarez. Ballard, Hamer, Juarez.'"

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During the marathon, there were signs all around Herndon that reminded him of the fallen troops. Two soldiers in army fatigues carried an exhausted runner across the finish line. Two wounded warriors crossed the finish line together, hoisting an American flag in the air. These runners fought through the pain and finished the race no matter their circumstances. Herndon knew he could do the same.

As the crowd cheered for Herndon, he repeated his own chant to himself: "Ballard, Hamer, Juarez. Ballard, Hamer, Juarez." Finally, after pushing through the pain for 3 hours and 40 minutes, Herndon crossed the blue and yellow finish line on his hands and knees.

Officials immediately pulled him into a wheelchair. Herndon was exhausted, but he did it — all in the name of his fallen friends. "The pain that I was going through is nothing compared to the pain that they went through," he said.