PELHAM, N.H. -- Brian Bishop was eating and stressing himself to death until a heart attack at age 28 got his attention. Now, after losing more than 100 pounds, he is a poster child -- literally -- for a national program to walk to a healthier lifestyle.

Bishop, 33, of Pelham, woke up in the cardiac care unit five years ago, with patients two or three times his age.

"That vision recurs to me on a daily basis because I don't want to go back there," said Bishop, who weighed 280 pounds at the time. "Everybody looked so unhealthy. I said 'I don't want to be here. I don't belong here. I need to fix my life."'

As part of the fix, he started walking, then running. After running in a 5 kilometer Heart Association race in Boston last summer, he found a forum.

He ran with a team his wife, Kara, organized for her law firm. When she contacted the association later for photos, she mentioned her husband was a survivor.

"We kind of said, 'survivor of what?"' said Angela Minardi, communications director at the Greater Boston Heart Association. "The guy is completely fit. He ran the race, he is young.

"She said he had a heart attack at 28 and my ears perked up ... let's meet him, let's get him in here," said Minardi.

Since then, Bishop has taken part in Heart Walks in Massachusetts and been the featured speaker at some walks. He's been on national TV, is pictured on a poster illustrating "Faces of Heart Disease" in a Heart Association traveling display and was the group's first-ever Lifestyle Change Award winner in the Boston area.

Bishop hopes to become a motivational speaker and perhaps write a book to help others change their lives, but finds it ironic to be giving fitness advice a few years after he dismissed it himself.

"Somebody said to me, 'You are under lot of stress -- overweight. You'd better slow down or you'll have a heart attack.' I said 'I'll deal with it when it happens' and less than three months later it happened."

Bishop soon joined a growing number of people walking for fitness or weight loss or to a better lifestyle. He started out walking 500 feet, then worked his way through higher goals. Now the commercial real estate developer and manager runs 50 miles a week, bikes, swims and trains with weights.

But for others, walking alone can do the trick. Ann Marie Harris has lost 150 pounds in two years by walking and eating better.

The Concord woman weighed about 350 pounds until after her second husband's death three years ago. She awoke one night and heard a voice saying she had to change.

She does not know Bishop, but their new lifestyles began the same way, heading to their kitchens and tossing everything from their cupboards.

For Harris, that meant "potato chips, ice cream, processed foods, canned raviolis, corn dogs -- I loved corned dogs -- canned clam chowder, pea soup."

And for both, step two led to the grocery store. Bishop and his future wife shopped for four or five hours reading labels. Harris, 58, stocked up on things like chicken, fish, vegetables and salads.

She starting walking alone, then joined a co-worker at a Concord retirement community during breaks. In two years, she dropped 150 pounds.

"Walking. That's all I'm doing, and eating right," she said.

But it's not easy for everyone to take the first step.

"I think there are a lot of barriers to that," said Michele Kerulis, a therapist and sport psychology consultant at the Chicago School of Professional Psychology. "One is that people believe the exercise itself or the walking itself or whatever the task is, is too difficult for them to even begin. Sometimes people don't realize if they take small steps, all of those little steps add up to goal accomplishments."

Many organizations stand ready to help, including the Heart Association, through its Start! program. Walking has "the lowest dropout rate of any physical activity," said Laurie Hambelton, at the Heart Association in New Hampshire.

The program includes walking and recognition programs for businesses, a wealth of online information and Heart Walks to motivate walkers and raise money for heart research.

"Ten years ago, it was very common for cigarette smokers to get two 15-minute breaks," Hambelton said. "Why not give employees two 15-minute walking breaks? If you do that, you will see fewer costs related to workers comp, absenteeism, employee turnover, and you're going to see improved productivity, morale and other benefits."

Benefits include weight loss, improved health and a brighter outlook, said Kerulis. A half-hour or hour of walking releases chemicals that decrease depression sometimes associated with low self-esteem, a common roadblock to changing eating habits or starting exercise.

But everyone stumbles, so it's important to allow occasional indulgences for a special dessert or not-as-healthy food, while resisting the urge to quit after slipups.

Bishop said he continues with his new lifestyle after slips because he can't bear to think he has wasted his effort.

"Are you kidding me? Just because I ate one thing?" he asked. "No. I ate that. I wasn't supposed to. I know it was wrong, but now I have to go walk it off."

STEPS FOR WALKING TO A HEALTHIER LIFESTYLE

* Set reachable goals.

* Use stairs, not the elevator. Park farther from the office or mall. "It's as simple as parking in the farthest spot at the grocery store or getting off your chair at lunch and walking around the building or the parking lot," said Brian Bishop, who lost more than 100 pounds after starting a walking routine.

* Walk with a friend or other walkers. An Internet search for "walking" turns up online support and programs that include everything from calorie-burning calculators and recipes and to virtual walking groups. Any kind of network like that can show individuals who are who are having hard time, that there are possibilities to being successful and that everybody starts with step No. 1," said Michele Kerulis, a therapist and sport psychology consultant.

* Buy new sneakers.

* Work up to walking 30-60 minutes a day most days of the week, recommended by the American Heart Association for good health and maintaining a healthy weight.

* Combine walking with healthier eating.

* If you fall off the wagon today, start again tomorrow. Ann Marie Harris, who lost 150 pounds by walking and eating better, stays motivated after slipups by focusing on benefits like feeling better about herself, while watching her blood pressure and cholesterol drop.

* Consult your doctor before beginning any exercise program.