A simple tribute meant to honor a grieving family and the service of a soldier from East Tennessee is now a national movement.

"It really helps in the healing process but it's just a true act of love," said Greg McReynolds admiring an American flag folded tightly inside a shadow box with a race bib. 

A one-time stranger ran with that flag in a marathon to pay homage to Greg's son Austin, a combat medic who died just days after his 21st birthday.

"He was run over walking down the road by a drunk driver who happen to be in the military and (Austin) was left there. That's a tragedy, but there is a little bit of shame about it because he didn't die in action, he wasn't killed by the enemy or anything," said McReynolds, a former military helicopter pilot.

The only shame runner Richard Clark, a former Army paratrooper, found in Austin's story was that a young man devoting his life to serving others was killed under such senseless circumstances.

"I don't know, it just felt right," said Clark reflecting on a social media post he saw about Austin and why he felt compelled to pay tribute to the young soldier and his family. 

In the spring of 2015 he wrote to the McReynolds family and explained his plan to run a marathon with an American flag to honor Austin and promised to mail them the flag after the race.

"You don't want your loved one to be forgotten so for a total stranger to reach out ... it was special ... it was healing for us," said Austin's mom Trista McReynolds. 

She and her husband were so moved by Clark's gesture, they drove from their home in East Tennessee to Grand Lakes, Ohio and surprised Clark at the finish. It was the first time they met face to face, and that moment birthed a movement.

"I've got runners lined up all the way through December (and a race) in Honolulu," said Clark who named the movement "Flags 4 Fallen" and the Facebook page now links runners with the families of fallen military troops and first responders. 

It is an opportunity open to anyone willing to buy a flag, run a race and mail the flag to a family grieving the loss of a loved one. In the last two years dozens of runners have signed on.

"I schedule this through my iPhone most of the time, but it wouldn't be what it is without runners volunteering with big hearts," said Clark.

Last Saturday, Greg and Trista McReynolds made T-shirts and carried flags during a 5K race in Knoxville to honor the lives of three servicemen killed in action during the war in Vietnam: 1st Lt. Sterling Cox, Warrant officer James Petteys and Private first class Garfield Langhorn.

"Knowing that you have helped somebody get through a rocky time in their life and take another step forward is just very satisfying," said Greg McReynolds.