Age was creeping up, and Linda Garrett, 67, decided to do something radical.

She went into the kitchen, propped the iPhone on a soup bowl, and recorded a plea to CNN's Dr. Sanjay Gupta to be part of his Fit Nation triathlon challenge. She wanted to be chosen as one of six Americans - among 200 applicants - who will be trained and equipped to compete for the first time in the grueling sport.

Garrett, a retired school nurse, had never swum a lap, never clipped into a bike pedal. And running was her biggest fear.

"I'm not terribly athletic and have always been 'thick,' as my mother used to say," she told CNN. "I married my high school sweetheart 46 years ago, and he still remembers when I got the high-jump bar caught between my legs in gym class, resulting in massive bruising. . . ."

That sweetheart, Jim Garrett, sat beside her the other day in their Haddonfield home and laughed lovingly at the memory. "That bar," he said, "was about a foot off the ground."

Of course, Linda Garrett was chosen for Fit Nation.

In September, if all goes well, she will swim a half-mile in the Pacific Ocean off Malibu, bike 18 miles, and run four.

Her acceptance into the competition, however, is just the latest step in a remarkable awakening and transformation.

Five years ago, on her way to work at a school in Laurel Springs, Linda Garrett drove by a new gym, Bell's Bodies Fitness, close to her home. After several passes, she finally went in.

"You have to fight inertia," she said. "I'm healthy. I have good genes, but I wanted to keep it going."

She semiretired in June 2013, but still works three mornings a week at a school for autistic children in Woodbury. She goes to the gym five or six times a week, and rarely misses Saturday boot camp, where her feats include flipping car tires.

Chris Bell, owner of Bell's Bodies, likes to say he brought out her "inner athlete."

Because of Linda Garrett, "nobody is allowed to say, 'I'm too old for that,' " says Bell. "No, you're not. Because Linda's not. Every year we elect an MVP, somebody who commits heart and soul to fitness. Linda is that person."

Last summer, Bell persuaded her to do a "mud run" on a horse farm in Shamong. "I skipped the 12-foot wall," Garrett said. "I didn't want to break a hip at this stage. I didn't jump the fire, either."

Her grandchildren hosed her off. She wanted more.

"That sparked something," she said.

Six years ago, CNN started Fit Nation. Instead of just talking about getting America in shape, Gupta, a medical correspondent, decided to do something.

The format is almost reality-show. Television and online viewers can follow six people each year as they get ready for their inaugural triathlon. Gupta does it with them.

Garrett is the oldest participant ever, by a decade.

"She's 67 going on 47, very young at heart," said Matt Sloane, the show's producer, who grew up in Villanova. "I expect her to do very well."

CNN gave her a $2,500 road bike and shoes. All contestants received a watch that records their workouts and shares the data with a trainer in Atlanta, who cracks the whip if necessary.

Garrett found out in December she was chosen, and all six went to Atlanta for a week in February.

"It was like Christmas every day, with workouts," Garrett said.

Her first day in the pool, "I swallowed a lot of water," she said. But after a week, she learned to breathe on both sides. She got prescription goggles so she can see, and is up to 45 laps at the local pool.

In May, the show will give her a wet suit, because the ocean is cold.

"They told us we can't drown in a wet suit," Garrett said. "So that's all I needed to hear."

She already has suffered a setback. Near Atlanta, the group hiked up Hawk Mountain. On the way down, her knee, which had been cranky, began to hurt. An MRI showed a big meniscus tear.

When she had arthroscopic surgery Feb. 17, CNN came to record it.

Garrett is back in the pool and working out at Bell's Bodies. She bought a training stand and rides her bike in her basement, gently now. No running until April.

"I'm really proud of her," said her son, Michael, 37, an annual Broad Street runner. He has already booked his hotel in Malibu.

Jim Garrett, of course, will be there, with other family and friends. He and his wife joke that he was the jock in high school, that he "front-loaded" all his athletics and now just plays golf, while Linda has "back-loaded" her athletic career.

She regards all this as "an incredible gift."

"I wanted to see what I could do at this age," she said. "And I will finish. I don't know where I will be. They might be turning the lights out, and the cops might be shooing me along. But I'll finish."

215-854-5639 @MichaelVitez