HER FATHER DIED SUDDENLY of a heart attack at 54. Now here was Susan, in her early 40s, rushing to her doctor’s office with a terrifying constellation of symptoms: worsening chest pain, chronic fatigue, aches throughout her body.

Susan’s doctor ran a standard battery of tests. The initial results came back negative and she exhaled, but she knew that relief would not last long if she continued on her perilous path. Susan’s health had spiraled out of control. She found herself succumbing to the temptations and shortcuts that challenge our resolve every day. “My weight,” she confided in an e-mail to me, “had skyrocketed to the highest it had ever been.”

One year ago, spurred by the memory of her father and alarmed by her physician’s warnings, Susan made a resolution to transform her lifestyle and reclaim her health.

Every New Year, millions of Americans like her resolve to do the same. Memberships in health clubs soar and diet books fly off the shelves, but the fitness fervor is fleeting as it becomes clear just how difficult it is to fundamentally alter our unhealthy habits, our toxic environment, and most importantly, how we think. The task is especially daunting, we quickly realize, when we endeavor to accomplish it alone. Susan vowed not to become another failed New Year’s resolution statistic. When she read in The Journal about Shape Up Rhode Island, a statewide nonprofit wellness competition that I created to promote healthy living through community building, she knew she had found a solution.

As Susan and thousands of other participants have learned, Shape Up RI is more than just a weight-loss and exercise program. It is a grassroots community organization that calls upon Rhode Islanders of all fitness levels to come together and work together in pursuit of a healthy lifestyle.

The idea behind our program is simple: Teamwork and support from our social networks, combined with a dose of friendly competition, can provide a potent prescription for achieving long-lasting behavior change.

Excited by this new concept and encouraged by her doctor, Susan logged on to our Web site and took a chance by joining a team of people she had never met from a nearby town. And it worked. Over the next four months, Susan and her teammates supported each other as they worked hard to meet their personal fitness goals. Because of conflicting schedules, her team members never met in person. Instead, they communicated online daily, and Susan looked forward to tracking their success and sharing fitness ideas with her newfound health partners on the Shape Up RI Web site.

While she admits hitting plateaus and facing periods of extreme frustration during the three-month program, she reports that the support of her teammates propelled her forward. As their friendships grew stronger, Susan found herself driven to succeed by a desire to make her companions proud.

She went from walking rarely to walking daily. She adopted new eating habits, moving to smaller, well-balanced meals and increasing her consumption of whole grains, fruits and vegetables. Her new sense of vigor engulfed her whole family, with her children choosing healthier meals and her husband finally joining her on daily walks.

Through her own hard work and determination, motivated by constant encouragement and accountability from her teammates, Susan lost 32 pounds during in our program.

Her success — and a growing body of medical research — suggests that one solution to the national obesity epidemic may lie in our ability to bring communities of people together for the common purpose of altering our collective lifestyle.

“The impact of knowing you are part of something greater than yourself has been life changing,” said Susan in one of the hundreds of e-mails I have received from successful Shape Up RI participants. “This program hasn’t just been about losing the weight as much as it has been about taking back my health and helping others do the same.”

In 2007, our family of 7,000 participants together exercised for 328,000 hours, walked 2 million miles and dropped 14 tons. This year, my goal is to engage 15,000 participants in our community campaign for a healthier Rhode Island. I hope readers across the state, inspired by Susan’s story, will visit our Web site at www.shapeupri.org and turn their New Year’s resolution into reality by joining us on this collaborative journey.

Rajiv Kumar, a student at Brown Medical School, is the founder and chairman of Shape Up Rhode Island.