Before Christine Lanning started training for her first marathon two years ago, she hadn't run even a mile in her life.

But after five months of structured training, she finished the Honolulu Marathon in 5 hours, 20 minutes — and with a newfound sense of what she could accomplish.

"My husband thought I was insane," Lanning said, laughing. "He said, at the end, he didn't think I'd ever do it."

But she did — and now she's training for another challenge: her first triathlon.

(It helps that her husband bought her a road bike for Christmas.)

"It's kind of the next thing," said Lanning, 34, of 'Aiea. "I thought, I've done the marathon and that was exciting ... Know I can put my mind to doing something, I can do it."

Lanning is one of hundreds of people expected to train for — or at least seriously consider participating in — their first triathlon this year.

Some are lured by the challenge. Some use triathlon training as a way to get into shape. And others are just hoping to find a sport — they have a choice of swimming, biking or running — they'll continue for the rest of their lives.

And there's no more popular time to start training than January.

"It's after the holidays and people want to get their bodies reawakened, the muscles activated," said triathlon certified coach KC Carlberg, owner of Try Fitness. "(Triathlon training) puts all those systems into action."

Like many first-timers, Lanning enrolled in a cycling program with Try Fitness. She hadn't been on a bike for years.

"It feels so weird," said Lanning, who is planning to participate in the Ford Honu Half-Ironman Triathlon, May 31 on the Big Island. "I never had a bike with gears!"

Carlberg recommends those interesting in participating in their first triathlon to work on their bike skills early. It's the one part of the race that requires more competence, especially to stay safe.

"For the first couple of months, we're base-building," Carlberg said. "So in addition to cycle training, we go over skills and techniques, how to become more efficient when cycling. You could have a great swim, but if you push yourself too hard on the bike, that could really affect your run."

While most triathlon training programs start in March, Carlberg said it doesn't hurt to start moving now.

"You shouldn't start training from the couch," she said. "You should have already done some base-building."

Lanning chose to enroll in a training program — which can cost between $350 to $450 for 12 weeks — because of the camaraderie you find in a group setting. It's not required, but the structured training does help.

"I find it's very helpful for me to be in a group, in that supportive environment where people are trying to achieve the same thing," she said. "It makes all the difference in the world."

The benefits of training for a triathlon go beyond muscle definition and weight loss.

Like marathons, triathlons push people to their limits. They take them out of their comfort zones and show them that with proper training — and a positive attitude — you can accomplish more than you think. And you're doing something healthy and good for your body.

"It's really nothing they've ever experienced before," Carlberg said. "They're nervous, but they're willing to try this and I think that's what makes this really exciting. It's people willing to commit to 12 weeks of training to achieve a goal. It's that willingness to take on something new ... That really builds confidence and self-esteem."