This weekend about 30,000 people will hit the streets of Fort Worth for the Cowtown Marathon races.
On Saturday's 10k, Jonathan Silk will be among those pounding the pavement.
You can often hear Silk before you even see him, not just by his foot steps and breathing as he runs, but also by his chest.
"If you're around me, once I get my heart rate elevated you will hear the ticking," Silk said.
"Sometimes it catches people off guard, so if I'm working out with someone I usually warn them ahead of time."
The sound is a clicking or ticking in his chest, and it's courtesy of a carbon fiber heart valve that Silk required after being injured in the Army in southern Iraq in 2004.
"We got engaged with a rocket propelled grenade (RPG) and it hit the ground in front of me about 15 feet," Silk said. "It did not detonate, or I wouldn't be here if it did. Then it kind of ricocheted up, broke apart, but I got hit in the chest with the shrapnel."
Thanks to his body armor he was just bruised and continued to fight as eight other soldiers were seriously injured as well. Silk noticed the bruise on his chest after his unit returned to safety from the battle, but months later the endurance athlete was struggling to run.
"You know, sucking wind, and I kept thinking, 'Here I am trained as a warrior, it's got to be me,'" he said. "'What's wrong with me?' But really it was the injury."
An injured heart valve, the mitral valve to be specific, required surgery. Doctors first tried to repair the torn valve, but in the end Silk got an artificial replacement.
He recovered from the surgery and worked to stay in the Army as he wanted to reach his goal of becoming a commander. He did so in a tank unit in South Korea. He also served as an adviser to the Afghan National Police in Afghanistan.
Now the Massachusetts native calls North Texas home after 28 years in the Army and retiring last December. He works at UNT Health Science Center as the new executive director of leadership development, and on Saturday he'll be running the 10k – ticking and all.
"It's good to hear, if you don't hear it there's a problem," he said.
And if you don't hear Silk's chest ticking, you'll be able to see him on the course proudly carrying an American flag he had with him when serving in Afghanistan.
"One of the reasons I run with the flag is to create awareness," he said.
It's an awareness for veterans, wounded warriors, their families and to help veterans get back into the community as part of Team Red, White, and Blue.
"And we focus on doing that through physical fitness and the social benefits of it," said Silk.
It's that kind of fitness and benefits that helped him after his injury. Now the wounded warrior works to give back to his fellow veterans by running in solidarity with them, thanks to a ticking heart valve and his passion for leadership.
"Yeah, I call myself the $300,000 man," he joked.
He also has a blog called "I Tick When I Run," where he talks about the mitral valve replacement and his efforts in the community.
"I love what I'm doing here," he said about his work at UNTHSC.
Saturday's 10k will be his second Cowtown appearance.
Silk received a Purple Heart and a Bronze Star for Valor for his wounds suffered in Iraq.