Larry Hecker, 89, of Great Falls trains with Brett Ednie at Worldgate Sport & Health in Herndon. (Shamus Ian Fatzinger)

Knees shaking, breath trembling and head aching, Larry Hecker encountered constant pain with every step up the stairs.

Decaying muscles caved in on a wounded heart, which beat for the loving wife he lost to cancer a few months earlier.

Hecker’s 89th year lay not far ahead, close enough to see but perhaps too far to reach. But he wasn’t about to quit.

Just a few months later, the Great Falls resident found himself in a gym, turning back the clock. Walking on the treadmill soon gave way to jogging; lifting a dumbbell turned into 30 sit-squats in a row; raising a racket progressed into full-fledged games of squash, his free-flowing swings catching every shot flush and leaving his awestruck trainer shaking his head.

Between hitting countless shots on the squash court and scurrying from one exercise machine to the next, Hecker is the product of a jarring transformation that turned an old man fighting disease into a spirited retiree eager for the next challenge. Although aimed at rejuvenation, it’s a change rooted in loss.

The death of his wife, Clare, 85, in July 2011, left Hecker sad and exhausted. As his movement slowed and his breathing worsened, he decided to fly to Tucson to seek help from his oldest son.

Before doing that, though, he paid a visit to his doctor.

“I came in and told him what I wanted to do, and he said, ‘You’re not going anywhere,’ ” Hecker recalled. “I said ‘Why?’ And he said, ‘You’re going to the emergency room.’ ”

The doctor said Hecker’s lungs were in terrible shape, although he was unable to provide a specific diagnosis. When a friend working at the Mayo Clinic in Rochester, Minn., pleaded to see him, Hecker soon found himself on an airplane.

After running a myriad of tests on Hecker, who was confined to a wheelchair, doctors determined that he had pulmonary fibrosis, a disease that scars or thickens the lungs, making breathing difficult. They weren’t sure how much of the damage they could recover, but they gave him medicine and suggested he get back into an athletic routine.

That’s when Hecker decided to take charge of his life.

“I came back and told myself, ‘I’m going to beat this thing, and someday I’m going to be back on the squash court,’ ” Hecker said.

That desire to return to the court traces to 1974, when he was sent to Saudi Arabia to work as a chief pilot for Trans World Airlines. Toward the beginning of their three years living in Jeddah, Hecker and his wife noticed a nearby structure containing chicken wire and a group of people looking down from an elevated platform.

“I said, ‘It must be a cockfight,’ ” Hecker recalled. “We go up and look and see two guys on this cement court with cement walls with what look like two tennis rackets. And they were having a great time, dripping wet. I said to my wife, ‘This looks like fun.’ ”

The next day, Hecker went with his wife and daughter to buy three bamboo squash rackets for $6 each. An obsession with this strange new game — a high-speed racket sport played by two players in a four-walled court — was born.

Eager to learn more about the game, Hecker approached a Pakistani man named Faquier, who lived in a hut between the squash and tennis courts near the U.S. Embassy. Faquier, a squash coach, gave the curious American daily lessons; within two weeks Hecker was proficient enough to play in daily round-robin tournaments against squash enthusiasts from Egypt, Balta and the United States.

It seemed a strange new hobby for Hecker, who played football for the University of North Carolina at Chapel Hill, in the 1940s. He was captivated by the sport’s blend of physicality and strategy.

“If you’ve ever seen two good squash players, it’s like chess on concrete,” Hecker said. “It’s a game, like golf, that you can play to some degree all your life. Once you learn the fundamentals and can play with some degree of ability, you get hooked on the game.”

Hecker frequently found time upon his return to the United States to play squash with his daughter and win several local tournaments, even as he climbed into his 60s and 70s. This year, he has taken it up again and found a new partner: personal trainer Brett Ednie, who has helped guide Hecker on his road to recovery.

Working out of Worldgate Sport & Health in Herndon, Ednie began conducting one-on-one rehabilitation training sessions with Hecker in November. Ednie remembers the first minute of the first exercise they did, when Hecker began coughing incessantly and had to quit when he struggled to breathe.

Now, after months of difficulty, Hecker is increasing his physical capacity with every workout, and he’s finally free from the shackles of his oxygen machine and medication. A high-calorie diet full of protein and carbohydrates has helped him go from 120 pounds to a healthy 145 pounds in the past eight months.

Hecker endures his grueling one-hour training sessions at the mercy of Ednie with enthusiastic dread. Although Ednie pushes him to hit new marks at every machine, Hecker holds his trainer to one stipulation: Each workout must begin with 10 minutes of squash.

“He’s always in a good mood,” Ednie said. “He never has anything bad to say. He’s always smiling and saying hi to everyone, so it’s really a fun part of my day every time I see him. There’s always a story; we talk about politics, current events, football, everything.”

A father of six, grandfather of 12 and great-grandfather of four, Hecker doesn’t plan on backing down anytime soon. Just like Clare, who lived twice as long as doctors predicted after the cancer diagnosis, Hecker won’t let disease or hardship drag down his spirit.

“You just have to say to yourself, ‘Yes, I can, yes, I can, rather than, no, I can’t,’ ” Hecker said. “You have to find the best quality medical help, and if it has to do with your body, get your body in tip-top shape and keep it there. It’s that simple.”