A Marine has gone viral after he dragged himself across the finish line at the Boston Marathon after both his legs "just gave up."

Here's what we know

Micah Herndon is a 31-year-old Marine veteran who served in Afghanistan. While he was deployed there, two Marines he was serving with and a British journalist were killed by an improvised explosive device. One of these men was his best friend, Matthew Ballard.

"Survivor's guilt, it's real," he told the Washington Post. "I definitely have it because I was the lead machine-gunner on that convoy and I didn't see that bomb that was buried. I live with that every day."

Herndon said that he wanted to run the marathon to honor their memories.

But around mile 20 out of 26.2, Herndon's Achilles tendon began to hurt. He tried to power through and keep running, but by the time he reached mile 22, he was reduced to a "low crawl."

Volunteers at the race ran over to him, but he refused their help. He insisted on dragging himself down the homestretch and crossing the finish line before he would allow them to help him into a wheelchair.

"The pain that I was going through is nothing compared to the pain that they went through," he told WBZ-TV. He said that he kept saying the names of the three men who died over and over again to keep pushing himself. "I just repeat: 'Ballard, Hamer, Juarez. Ballard, Hamer, Juarez.'"

Later that day, the Post reported, Herndon said that hoped to use his fleeting fame to raise awareness of the difficulties that veterans can face at home.

"If we can do something about it, that's all I care about," he said.