Halfway through a 50-mile bike training session with wind and rain blowing in your face, what keeps you going? Why didn't you stay home?

Like all athletes, triathletes are motivated to train and compete for different reasons. It can be as simple as a goal to get fit and lose 15 pounds or joining a group of friends to raise money for a charitable cause. On a much deeper and intimate level, pushing your limits of physical endurance or dedicating to a loved one the effort to cross the finish line provides the inspiration.

A triathlete since 1982, Brad Werntz was initially motivated by the novelty of the new sport and later by his fellow triathletes participating in the Wisconsin Ironman, the course of which passes his home. "It's hard not to get inspired when an Ironman starts at your door every year," said Werntz, a principal of Pemba Serves, a Madison, Wisconsin-based firm representing makers of outdoor industry products.

There are two kinds of motivation, according to John Anderson, of the Center for Sports Psychology in Monument, Colorado. "Intrinsically, it's what's within you driving you to compete. Extrinsically it's 'I'm doing this for reason X, like people competing in a breast cancer run or walk," he said. "When you look at the individual and what contributes to their functioning most effectively, it's always some kind of combination of the two."

Consider Dan Rotert, a management consultant in Madison. When Rotert turned 40 in 2004, he was overweight and unhappy with his lifestyle, so he made it a goal to finish the Chicago Marathon. In addition to improving his fitness, he decided to honor his parents, who died of cancer, by running to raise funds for the American Cancer Society.

"I needed to do something and I had a cause to do it for," Rotert said. "When I crossed the finish line at the Chicago Marathon, that was a life-changing event for me. I reached a level of satisfaction in terms of personal accomplishment that I had never achieved before."

Rotert has since finished near 20 triathlons in distances from sprints to a full Ironman.

His motivations have changed over time. "My son was diagnosed with Type 1 diabetes," he said. "That really hit home that I needed to live a healthy lifestyle to set a good example for him. The more I dedicated myself to it, the more it became a dependency for me in terms of managing stress and defining who I am as a person in my own mind."

After successfully completing a full Ironman, Rotert took a year off. The break wasn't positive, however. "I realized I didn't have the same sense of satisfaction in myself. I wasn't managing my stress very well and was on antidepressants. My wife said, 'You are just a happier and better person when you are focused on doing long distance events.'"

Anderson says he helps Olympic-caliber athletes motivate themselves for competition. "One of the things I talk to athletes about is their power. Where does your power come from? It comes from how you process your thoughts. Are you so critical that your training regime falls short of what you'd like?"

According to Anderson, self-criticism can have both positive and negative influences. "We talk about giving your power away," he explains. "The questions that raise doubt or concern, you tune in to that. And that is giving the power that you generate from within to others."

He continues: "That kind of criticism in excess can be detrimental but can also be a driving force to get you to move forward. It is okay to engage in productive criticism that questions your power appropriately. Where everyday athletes fall short is when we go out for a long run, bike or swim and we don't always think about the best possible outcome."

As a management consultant, Rotert travels four days a week. Fitting in training for an Ironman can be a challenge, mentally and physically. "Getting in all the training is tough," he said. "When I get back to my hotel room, often the last thing I want to do is put on my running shoes and go out for a couple of hours. When I get home the last thing I want to do is climb on my bike and go for a long bike ride."

But Rotert usually finds the reason and the energy. "I know I have the event in the future. And when I finish that, it charges me for the rest of the year. I carry that with me," he said. Rotert says he often wears a triathlon event T-shirt under his dress clothes. "That helps me remember why I do it and what it's all about," he said.

Werntz said he relies on training regimes to fuel the fire. "It's a commitment you make that is beyond the dollars and time spent," he said. "It's a framework for output. Without a framework it's really difficult to jump in a cold lake or ride 40 miles before everyone wakes up. It's made me a better age-group athlete. We all struggle with fitness as we enter middle age. It's certainly kept me younger. For that I'm thankful."

Rotert is a member of a multisport training group and feeds off the experiences of his fellow triathletes. "It's full of people who have different motivations but a common purpose," he said. "On those days when it's tough to keep plugging along, there's always someone on the team that can pump you up."

He also relies on his coach, Cindi Bannick. "On a race day, Cindi told me the hard work was already done and today was a celebration. 'You've prepared for it, just enjoy it,' she said. That's what I think about. I make it a party. It's the happiest day of the year for me."

Anderson suggests repeating a mantra, like "T3: trust the talent," to keep you relaxed and strong on race day.

Whatever drives you to compete, make sure you spend as much time nurturing the motivation as you do swimming, biking and running.