(CNN) -- Matthew Sanchez had rarely seen his father cry. But when Rudjard Hayes looked at the X-rays of his son's spine after a high school football accident, he held his wife close and broke down, not knowing that his son could see him.
Matthew Sanchez, now 20, relearned how to walk at Shepherd Center using the parallel bars.
Hayes was used to watching Sanchez get knocked to the ground during games and then get back up, but that game in 2004 was different: After getting knocked down, Sanchez, then 15, could not move.
"I knew it was serious, but it didn't really sink in until I saw the X-rays for myself," said Hayes, who lived with his family in Sharpsburg, Georgia, at the time.
Sanchez's C5 vertebra (in his neck) was fractured.
"I knew the chances of him recovering were basically zero. But I hoped and prayed 24-7," Hayes said. "We are a very faith-based family and believe that you trust the people that are there for you, and things are going to be OK. God will see you through it."
Doctors at Shepherd Center in Atlanta, Georgia, operated on Sanchez's neck, putting in a plate, screws, cables and a piece of bone from his leg.
According to Dr. Donald Peck Leslie, medical director of Shepherd Center, less than 1 percent of people with this type of spinal cord injury regain full physical abilities.
But Matthew Sanchez was destined and determined to be in that elite group. Days later -- and much sooner than anyone thought possible -- Sanchez started regaining some movement. Watch part one of Matthew Sanchez's odyssey »
Five weeks later, after intensive therapy, Sanchez walked out of Shepherd Center. After six more months of therapy, his sense of normalcy returned. Two years later, he could be a competitive athlete again.
"I just think some people are a little bit more motivated. Matt was an athlete, so he knew how to work hard," Cathi Dugger, Sanchez's physical therapist, told Dr. Sanjay Gupta, CNN's chief medical correspondent.
Today, five years after his injury, Sanchez has seven triathlons under his belt.
Twist of fate
Sanchez's extraordinary recovery was made possible by an unlikely stranger. When the teen was knocked to the ground, the doctor for the opposing team, Dr. John Henderson, rushed to his aid. Knee-deep in mud, Henderson held Sanchez's head in traction for 45 minutes, preventing anyone from moving him. Henderson also insisted Sanchez be transported by helicopter instead of ambulance.
Sanchez's mother credits Henderson, in part, for the favorable outcome.
"Our family believes that Dr. Henderson was our angel that night. Our high school did not have a team physician, and I feel certain Matthew could have been moved had Dr. Henderson not prevented anyone from touching him until he could be properly transferred," Lorraine Sanchez Hayes said in an e-mail to CNN.
Had he been moved, his mother believes, his injury would have been made worse. Watch part two of Matthew Sanchez's odyssey »
One year after the accident, the family learned that Henderson's son, Army Ranger John Henderson Jr., had been killed in Afghanistan.
"This man had been instrumental in saving our son's life, only to have his own [son's life] taken," Sanchez Hayes wrote.
While most college students spend their summers relaxing, taking extra classes or working to earn money, Sanchez, now 20, chose to spend the past 2½ months giving back to the doctors who put him back together in the best way he knew how: a 4,350-mile fundraising bike ride. See photos from the bike ride »
In part to memorialize Henderson's son, and in part to raise money for Shepherd Center, Sanchez and three friends -- Anthony Orig, Marina Fleming and Jonny Cromwell -- set out in May on a cross-country expedition to benefit the SHARE initiative, as the We Ride For Shepherd team.
Shepherd Center is home to SHARE -- a partnership between the military health care benefits program, philanthropist Bernie Marcus and private donations. Through SHARE, veterans of the wars in Iraq and Afghanistan with brain injuries, spinal cord injuries and chronic pain can get specialized, cutting-edge treatment at Shepherd Center, and receive housing assistance for themselves and their families.
"Our goal is to educate the VA about what we have available," said Dr. Darryl Kaelin, the Shepherd Center physician who oversees the SHARE initiative. He said that many of the smaller Veterans Affairs hospitals might not be aware of the resources available at Shepherd Center.
Kaelin said one of Shepherd Center's main focuses is to help people move on with their lives after a catastrophic injury and regain their independence.
That's what brought U.S. Army Spc. Dillon Cannon to Shepherd Center as a SHARE patient. Cannon had been in Iraq for about a month when he was shot by a sniper in 2006.
He admires Sanchez's fundraising effort. "Why military personnel? Out of the kindness of his [Sanchez's] heart. It shows that people like that go above what they have to do. I mean he could be working -- making money for himself -- but he's trying to help out people like me," Cannon said.
Hayes said that he is proud of his son for completing the cross-country journey, but he's even prouder that Sanchez wants to give something back.
Sanchez said he couldn't think of a better way to show his appreciation. "These men and women are over there... risking their lives every day, and we feel like they deserve the best treatment possible," he said after completing his 78-day bike trek.