Ken Dockery’s coaches in high school always made him run extra laps after practice because they thought he was out of shape. But it wasn’t until Dockery, a 48-year-old pastor in a Cleveland suburb, reached his 30s that he learned the true source of his fatigue: Instead of three flaps that open his heart valves to regulate blood flow from the organ, he had only two, a birth defect called bicuspid aortic valve disease (BAVD).

Amid undergoing corrective heart surgeries in 2003 and 2015, Dockery has completed countless competitive physical pursuits, and Saturday, he’s running a marathon in Stockholm to honor his cardiac surgeon who is from Sweden. Through it all, he wants to inspire others and show what’s possible in spite of suffering from a serious heart condition.

“I just figured that if I don’t have that much time, I’m gonna do as many things as I can to encourage and help others,” Dockery, whom doctors now expect to live a long, healthy life, told FoxNews.com. “I think that is what will be more satisfying and fulfilling in life rather than just seeing what I can do for myself.”

About 2 percent of the U.S. population has BAVD, according to the Cleveland Clinic. Although doctors are trained to detect heart murmurs in babies, some miss them, and those patients, like Dockery, don’t realize they have BAVD until they begin experiencing symptoms like fatigue and chest pressure later in life.

In January 2003, Dockery underwent a Ross, or “switch,” procedure, wherein surgeons replaced his aortic valve with his pulmonary valve and transplanted a donor pulmonary valve to restore proper heart function. The aortic valve lies between the left ventricle and the aorta. The left ventricle is the lower-left chamber of the heart that stores blood before it’s pumped to the aorta, the largest artery, and then to the rest of the body. The pulmonary valve closes the lower-right chamber, or right ventricle, and opens to pump blood from the heart to the lungs.

A Ross procedure is usually done in children whose hearts are still developing and can see their pulmonary valve continue to grow post-op, as well as in women of childbearing age, who cannot take blood thinners without potentially harming their unborn children. Patients with a mechanical aortic valve must take blood thinners.

The operation was also a good option for Dockery because of his age and active lifestyle, said Dr. Gosta Pettersson, vice chairman of the department of cardiothoracic and cardiovascular surgery at the Cleveland Clinic. Pettersson inspired Dockery to run the upcoming marathon in Stockholm, as Pettersson performed both the Ross procedure on Dockery and later a reverse Ross procedure.

The Ross procedure “means that you take the pulmonic valve, of a low-pressure system, and transfer it to the systemic system, which has high pressure,” Pettersson told FoxNews.com. “Some of these valves stretch out over time and become leaky, so that’s the drawback of the Ross procedure, and that’s what happened to Mr. Dockery.”

In the reverse surgery, Pettersson removed Dockery’s donor pulmonary valve, replaced it with his natural pulmonary valve, and implanted a mechanical valve in place of his removed aortic valve. Like the initial surgery, the reverse Ross procedure effectively helps the heart pump blood to fuel the rest of the body’s organs.

“I feel kind of bad about it because [the donor valve] was a tremendous gift that someone gave me, and it was in perfect condition when it came out,” Dockery said, “but now I have my own [pulmonary valve] back in its original spot.”

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He must now take blood thinners, but other than avoiding contact sports— which can increase the risk of excess bleeding after injury— he has maintained a normal lifestyle.

It was after his initial surgery that he began challenging himself with physical pursuits, like a coast-to-coast, 3,500-mile, 50-day bike ride in summer 2007 with his four children and wife, Renee, traveling alongside on a similar route by RV. He said he raised about $11,000, donating some to the Cleveland Clinic and using the rest to cover trip expenses.

“That was the trip of a lifetime,” Dockery said. “They’d go see something historical or go to a museum, and meet up with me the next day. We’d stay at a campground or in a Walmart parking lot.”

When Dockery grew restless with biking, he started running competitively. He participated in the Cleveland Marathon in 2009, completing the standard 26.2 miles, and in 2011 he did the Copperman Triathlon in Michigan, which involved a half-mile swim, 16 miles of biking, and 6 miles of running.

Dockery’s eldest daughter, Kelly Dockery, 20, described her dad as “a strong leader in our family.”

“I know me and the rest of my siblings all aspire to be like him, find a spouse like him, things like that,” Kelly, who is studying psychology at John Carroll University, in University Heights, Ohio, told FoxNews.com. “Our whole family is a lot closer because of the surgery, knowing each time we do something with him, it could be the last time.”

When Dockery’s energy began to wane leading up to the reverse Ross procedure in January 2015, he took some time off from running and biking. He underwent the surgery, stayed in the hospital for 10 days, underwent a few months of cardiac rehab, and hit the pavement again— gradually increasing his mileage and speed.

He developed a relationship with Pettersson and received clearance to do the Stockholm race with him beforehand.

“[Pettersson] seems very— I don’t know how to describe it— humbled,” Dockery said. “He emailed me twice thanking me yesterday to tell me how honored he was that someone would attempt something like this.”

Pettersson said it “means a lot” that Dockery is traveling to his home country for the marathon.

“As a symbol of what we can accomplish with heart surgery, I think it’s a wonderful thing,” Pettersson said. “We take someone who, in essence, has a deadly disease, and he can do whatever he wants to do.”

Pettersson added that he connected Dockery with his daughter Lisa Bearpark, who lives in Sweden and is studying medicine at the Karolinska Institute in Stockholm, and that he was excited for her to “get a little sense of what her father is doing.”

Pettersson pointed out that despite the high quality of Dockery’s mechanical valve, which is composed of an artificial diamond-like pure-lit carbon material, his heart will never function as well as a normal, all-natural human heart. However, in the 25 times he has performed the reverse Ross procedure since he invented it in 2006, he’s never had to go back into a patient’s heart and correct the mechanical or natural pulmonary valves.

Dockery said he’s approaching his future health one step at a time, just as he takes his races one mile at a time. For the Stockholm Marathon, he hasn’t set a time goal— he simply wants to cross the finish line.

“I want to try to not quit and get to the end,” Dockery said.