A few months from now, on his wedding day, Tyler Moon will give his heart to Amy Greene.

The heart that stopped beating two weeks ago, somewhere around mile 8 of the TC 10 Mile race.

The heart that a dozen strangers, doing chest compressions in shifts, restarted in the middle of Summit Avenue in St. Paul.

“This story, I don’t think it’s about me,” Moon said. “I just went for a run and a bunch of great people stepped up and just saved my life.”

But this story starts with Moon, a healthy 25-year-old from Sauk Rapids, a former college football player with no history of heart trouble. On Oct. 6, he lined up at the starting line of his first 10-mile race.

On his race bib, instead of his name, he wore an expression of his faith: Jesus Saves.

At mile 1, Moon passed his cheering parents and fiancée.

“He ran up, gave me a hug,” said Greene, also 25, from Minnetonka. “He was just running and looking awesome.”

Moon doesn’t remember much after that.

His family hurried up the course and spotted him again around mile 7, powering up a long hill. “He was looking great,” Greene said.

A mile or so later, for reasons the doctors still can’t explain, Moon’s heartbeat stuttered. It fluttered rapidly, erratically, uselessly in his chest. Ventricular fibrillation. As his heart lost the ability to pump blood, his legs carried him a few more steps.

Then he dropped, cracking his head on the pavement.

That’s where Dave Soucy comes into the story.

“I was probably 5 feet from him,” said Soucy, a radiology technologist at Regions Hospital in St. Paul and one of at least a dozen people with medical training who were in the right place just when things started to go very wrong for Tyler Moon. “Just in my peripheral, I see him stagger a little bit, and then — face-first, right into the asphalt, real hard.”

Soucy sprinted over. Moon’s face was a bloody mess, his breath came in agonal gasps, and the pulse under Soucy’s fingers was thready and weak.

More help came running.

“All these people were stopping, ‘I’m a nurse, I’m an EMT,’ ” Soucy said. “It was nice not to be alone.”

Tommy Carlson, a Regions nurse running the course, reached the scene just as Moon’s pulse faded and his heart stopped.

“We’re starting to run a full code right out there in the street,” said Carlson, who helped with chest compressions. Rescuers worked in shifts, maintaining Moon’s airway, throwing their body weight into the effort to keep blood pumping through his uncooperative heart. For 10 minutes they administered CPR, maybe 15. “You kind of lose your concept of time. You get tunnel vision.”

Finally, EMTs arrived with a defibrillator. One shock, and Moon’s heart thumped back into sinus rhythm. They loaded him into the ambulance and sped off to Regions. “I was amazed,” Carlson said. “Holy smokes, we did it.”

Soucy and Carlson headed back out on the course together, finishing the 10 Mile and saving a human life in the respectable time of 1 hour and 38 minutes.

At the finish line, where Moon’s family was searching for him, Greene’s phone rang.

He was at Regions, in the ICU, sedated, breathing through a tube and hooked to machines, his face bruised and broken by the fall.

Within hours, he was awake and breathing on his own. Within a week, he was trotting on a treadmill during a stress test.

For a man who suffered a concussion, facial fractures and a full cardiac arrest, Moon is feeling pretty good. He’d like to go back and finish the last leg of that 10-miler. They gave him his finisher’s medal in the hospital, but he feels like he hasn’t earned it yet.

He’ll need surgery to implant a defibrillator, but there should be enough time to recover before the January wedding.

Moon still has his crumpled racing bib, and its message: Jesus Saves.

“I’m just lucky I was literally saved on Earth,” he said. “I think that’s the most important thing, after Jesus. It’s the people Jesus put there.”

That list includes Soucy and Carlson. Grant Morrison, a Fairview physician out for a run. Jeni Rymer, a nurse anesthetist from Regions, who had been cheering the runners from the sidelines with her husband and baby. Paul Larson, a member of the National Ski Patrol working as a medical volunteer at the mile 8 checkpoint.

St. Paul firefighters Vince Adams, Matt Simpson, Ben Ham and Jason Yamamoto, and St. Paul police officer Heather Gustafson. Runners Allison Adams, Jesse Bueno and Nicole Williams, who jumped in to help. Steve Levens, who was heading medical communications along the marathon route. The EMTs, the hospital staff. The bystanders who called for help.

“I don’t know any of them. They had no reason to stop,” he said. “They were just trying to do the right thing.”