"We're quite a team," King tells PEOPLE. "We're thick as thieves. We got this."
The unlikely partnership sprang from a devastating 2012 wartime incident. On July 25 of that year, while on his second tour in Afghanistan, King was hit with an IED. He lost both legs in the explosion, and eventually wound up at Walter Reed Medical Center in Washington, D.C. There, he learned to live with the "new normal," which included using prosthetic legs.
It was slow going at first for the hard-charging soldier, who previously competed in the Army's arduous annual Best Ranger Competition.
"I was just learning to walk on prosthetics," King says. "After 10 minutes, I was exhausted."
He also encountered people from Achilles International, a nonprofit running club that pairs wounded warriors with guides who help them complete road races.
"I told them, 'I can't do a marathon,' " King recalls. "They said, 'Yes, you can.' "
Courtesy Melinda Boisjolie
King was soon paired with Cordani – who, in addition to running a major corporation, is also a longtime endurance athlete whose many athletic accomplishments include completing the notoriously difficult Ironman triathlon.
At first, King wondered whether Cordani would trust him as a co-athlete.
"You want to know if the guy in your foxhole is going to fight or fold," King says. "I showed him, I'm a sergeant in the U.S. Army."
He needn't have worried. Cordani only cared about helping his new pal make the best of the "new normal."
"My focus was to help him make his goal," Cordani says. "Goals have to be owned by the individual. But they need support. That's what I am there for."
Four marathons later, the partners-turned-buddies have developed a finely honed system of support and achievement.
During races, Cordani keeps a close eye on King, helping him maintain his pace, conserve energy, and avoid pitfalls – in particular, at water stations.
Need a little inspiration? Click here to subscribe to the Daily Smile Newsletter for uplifting, feel-good stories that brighten up your inbox.
"Water stations are a headache," King says. "Runners drink the water, and throw the cups on the ground."
The cups are waxy, which is problematic: "If I step on a cup, it turns into an ice skating rink," King says.
In order to keep King from skidding atop waxy cups, Cordani diverts to the station to grab his pal's water while the wounded warrior keeps running.
"I'm not in the traffic of runners, and I still get my water," King says.
Elsewhere, Cordani substitutes for King when encountering fans along the route.
"People are great," King says. "They want to high-five me."
Courtesy Melinda Boisjolie
As much as he would like to, though, King cannot respond to every high-five: "If I do, my arm will fall off. I would be exhausted."
He also would feel more pain. Running on prosthetics is tortuous, King explains: "By miles 12-17, my body is in pure agony."
To counter that, King wears headphones with Army cadence calls that bring him to his "happy place."
"If I break concentration to high-five people, I can't go to my happy place," he explains.
Instead, Cordani does the high-fives on King's behalf.
Overall, the key to the duo's success is to resist intrusions that will throw them off goal.
"I never allow things that happened to me to happen inside," King says.
The partnership works both ways.
"Cedric helps me because my focus is on him and not on myself," Cordani says. "If I'm in pain, I can box it. I suppress it, and move on. It's all about him out there."
Why does he take on the increased challenge of helping another runner while completing his own difficult race?
"I'm grateful to veterans for what they do for us," says the CEO, who was not in the military but whose grandfather served in the Navy in World War II. "Any opportunity to give back to the vets is a privilege."
Now, the seasoned partners are taking their team a step further: They plan to mentor another wounded warrior through the upcoming Boston Marathon.
The third teammate is Stefan LeRoy, a former Army Cavalry Scout who lost his legs to an IED while carrying a wounded buddy to a helicopter in Afghanistan in June 2012.
The can-do team of King and Cordani already are lifting their new partner toward his goal of completing the Boston Marathon.
"They help me in a silent level of spirit," LeRoy tells PEOPLE.
The running duo insists that their accomplishments are merely an example of what anyone could achieve.
Says King: "I want anybody who reads this to know, it's not about what happens to you, it's what you do about it."