In the spring, when Jane Kirton turned 70, her husband and a friend treated her to eight weeks of heart-pumping group workouts with a training program for the 15th annual Na Wahine Sprint Triathlon.

A few weeks before wrapping up prep for the all-women’s swim-bike-run event, held in Waikiki earlier this month, Kirton said she was delighted with the birthday gift that connected her with Try Fitness trainers and about 20 triathlete training buddies of various ages.

"I’m the oldest, for sure," said Kirton, flashing a smile and brushing back her short silvery hair. "I think it’s important to be around younger people and to train with them. You get a lot of support, and you can give a lot of support as well."

For Kirton, a registered nurse and nurse practitioner, linking up with others for exercise and athletics is key to staying active at a time when many peers are retiring and slowing down.

Her No. 1 pointer for folks trying to shed a sedentary lifestyle: "I keep telling people not to wait," she said. "Just get off the couch."

In addition to taking part in triathlons, Kirton runs road races and marathons, swims in open-ocean competitions and practices yoga daily.

One might assume the slim and affable Hawaii Kai-area resident is a lifelong athlete. But that’s not the case.

As a schoolchild, Kirton concentrated on getting good grades and paid little attention to sports, although she took swimming lessons and, while in high school, was a member of an aqua ballet group.

Kirton’s interest in triathlons and other sports began taking shape two decades ago, when she marked her 50th birthday.

At that time, she said, "A friend of mine suggested that she and I join the gym." Kirton, whose nursing work then included counseling people about the benefits of regular exercise, acknowledged that her own physical fitness was lackluster, and agreed to sign up.

"I ended up going just about every day for two years, and she never went back — not one time," Kirton said, laughing.

Kirton’s success in establishing a workout routine was tied to the influence of another friend, a woman she met in an exercise class at the gym.

"It was meeting my friend at the gym that kept me going for a long time — that obligation and camaraderie."

When their early morning gym class was canceled, Kirton’s workout buddy suggested that they start meeting for neighborhood runs.

"I said, ‘I’m not much of a runner.’ But she said, ‘Oh, it will be fine. We’ll run a block, walk a block. It’ll be great,’ and, sure enough, it was."

Shortly before moving to Hawaii in 1998 from California, Kirton signed up for her first-ever race, San Francisco’s Bay to Breakers 12K (7.46 miles).

The event stoked Kirton’s confidence to later sign up for Oahu’s Great Aloha Run and the Hono­lulu Marathon, which she has finished four times and plans to run again in December.

Kirton’s husband, Jim Roumasset, introduced her to ocean swimming on Oahu’s South Shore. She went on to enter the annual 2.38-mile Waikiki Roughwater Swim and the North Shore Swim Series, which includes four races ranging from a 1-mile sprint to a 2.3-mile swim.

Whether prepping for races or just maintaining fitness, Kirton said, "I’ve learned that you have to think about what your goal is and plan for that goal. Live in the present and take it step by step." She credits Iyen­gar yoga classes at Silent Dance Center studios in Moiliili and Kaimuki with helping her master that lesson.

A few days after taking part in the Na Wahine Sprint Triathlon, Kirton was pleased with her performance and said her planning had paid off. She finished the 500-meter swim in 11:01 minutes, the 12-mile bike ride in 50:51 minutes and the 5K (3.1-mile) run in 33:45 minutes.

Although Na Wahine is a competitive event, Kirton said, there was a palpable "group energy" along the race’s course, in that all 142 participants had their own goals and were also supporting one another.

"It was really about a group of women having fun with the sport."