What's even more impressive is that this fit woman is 46 years old. She also works. And is a mother of six.

Furthermore, her best time for a marathon is a noteworthy 3 hours, 52 minutes, and she didn't start running until she was 41.

After attending Punahou and the University of California at Irvine, Yim devoted herself to a life of professional dancing and teaching dance at Punahou.

Ballet was her forte. Her marriage to Dr. Ernie Yim, a pulmonologist at St. Francis Medical Center, led to a growing family. She managed to stay active in dance until she was three months pregnant with baby No. 5. At that point "it was just too hard to audition," she said. "So I went into early retirement."

The departure lasted quite a while.

"I went into hibernation for a good part of my life because of my children," said Yim, whose kids range in age from 9 to 21.

Began with triathlon

Five years ago, triathlon coach Raul Boca urged her to participate in the Tinman Triathlon. She said she didn't even know the three sports that constituted a triathlon.

Intrigued, she started to train, completed the race successfully, and was hooked. At that time the run portion was her nemesis. Now it's her favorite sport, thanks in part to logging 1,500 miles a year for the past five years with training partner Kenton Eldridge.

"I'm continually amazed that any person with such a demanding schedule as Brenda has can participate in so many sports activities," said Eldridge, who added that their running mileage this year will reach 2,200.

"She never misses a scheduled workout. She's always positive. She always has interesting stories to tell. She can talk nonstop even when she's running up Tantalus."

She and Eldridge ran up Tantalus four times per workout — totaling 20 miles of uphill running — at least once a week to train for Run to the Sun, a 36-mile race up Haleakala earlier this year. She also qualified for and raced in the Boston Marathon this year, yet struggled in the unprecedented heat wave.

In addition to participating in next month's Honolulu Marathon, she plans to train for the Canada Ironman Triathlon, a 2.4-mile swim, 112-mile bike ride, and 26.2-mile marathon in August. Having completed the Waikiki Roughwater swim several times, as well as half-ironman distance triathlons, she feels confident in her ability to tackle the three-sport challenge.

Yim's weekdays usually begin at 4 a.m. when her alarm goes off and her encouraging husband hears the standard plea: "Five more minutes!" The trick, she said, is to set the alarm for 15 minutes before you really need to get out of bed. "Once I get up, I can go."

She drops off her kids at school early and gets to her husband's office, where she is the administrator, by 9 a.m.

She cooks dinner every night, sometimes putting out food early so she can slip in another workout in the evenings. On weekends, she begins in the dark. "By the time I finish training, I'm back on taxi duty," she said. "I'm a master at juggling."

Looking ahead

Future goals include running a marathon in 3:49:59 before she turns 50, and participating in marathons in Chicago and Los Angeles, where her two oldest children attend college. An ultra marathon — maybe even a 100-mile race — is also a possibility down the road.

But right now she's focused on the Honolulu Marathon, and on staying healthy. Yim has matched with an anonymous patient and could become a bone marrow donor soon after the December event.

Meanwhile, whatever spare time she has is spent choreographing a show called the "Dancing Doctors" for hospital patients "who never get out." Taking apart her old costumes and dressing physicians in them, who proceed to dance throughout the hospital for a gleeful audience "balances who Brenda Wong was and who Brenda Yim became," she said.

Whether it's donating bone marrow, providing entertainment for those in need or lending a hand to fellow athletes during their events, her generosity is evident to everyone around her.