DAVID N. CAMPBELL’S path to creating and running a volunteer organization began when he heard about the 2004 Indian Ocean tsunami.

His response was something he had not seen coming. “When I heard about it, I was overwhelmed,” said Mr. Campbell, 72, a former technology executive. “In my gut, I knew I had to help.”

He had never been to Thailand, and his experience as a volunteer had been limited to overseeing a United Way campaign in Buffalo.

The one-week visit Mr. Campbell had planned turned into a one-month stay, and a new way of life. Ten years later, he runs an organization, All Hands Volunteers, a nonprofit based in Mattapoisett, Mass., that has dispatched 28,000 volunteers to 45 global disaster zones from Indonesia to the Philippines, Peru, Bangladesh and Haiti, as well as to dozens of domestic sites hit by tornadoes, hurricanes and flooding, including Detroit and Long Island and Staten Island after Hurricane Sandy.

The work is varied: rebuilding houses, packing knapsacks with school supplies for children, debris removal and basic gutting and cleanup. In exchange, All Hands provides volunteers with tools, meals and communal living arrangements at no cost.

“Now I’m a member of the Good for Nothing Club,” said Mr. Campbell, who does not take a salary. “We want to do good — for nothing.”

But sometimes the world does pay you back. On Tuesday, in Tempe, Ariz., Mr. Campbell is to receive a cash prize of $100,000 in recognition and support of his work.

He is one of this year’s six winners of the Purpose Prize awarded to Americans 60 and older who have had an impact on the world. The award was created by Encore.org, a nonprofit organization that’s building a movement to tap the skills and experience of those in midlife and beyond to improve communities.

A common spine runs among all of the winners: “An increasing number of people over 60 want to leave a legacy and do something that makes their children proud,” said Ann MacDougall, president of Encore.org. “They’re thinking about what’s going to be read at their funeral. Not that it’s right around the corner, but they start thinking in those terms.”

Now in its ninth year, the Purpose Prize will award $100,000 each to two winners and $25,000 each to four others.

Charles Irvin Fletcher, 76, a former microwave systems engineer, will receive this year’s other six-figure prize. After retiring, Mr. Fletcher, a lifelong horse lover, spent five years and 5,000 hours volunteering at a therapeutic riding center in the Dallas area dedicated to equine therapy for children with disabilities.

“While the children enjoyed the ride, I didn’t see any healing, and I thought more could be done and more should be done,” Mr. Fletcher said.

So he researched ways to provide science-based equine therapy. He met with medical specialists to learn about brain development and created a network of experts.

Then in 2001, he founded SpiritHorse International, a nonprofit based in Corinth, Tex., 30 miles north of Dallas. His ranch is now home to 31 horses and ponies, and is the headquarters for a worldwide network of 91 licensed therapeutic riding centers that serve children with disabilities in the United States, South America, Africa and Europe.

At Mr. Fletcher’s ranch in Corinth, roughly 400 children with disabilities, some as young as nine months, receive free weekly riding sessions on ponies with names like Buttercup and Peter Pan. The riders have a variety of medical conditions, including autism, Down syndrome, cerebral palsy, multiple sclerosis and spina bifida.

More than 5,000 children have been helped through the network since the gates first opened.

“I believe that horses can feel spiritual messages,” Mr. Fletcher said. “They can feel love. They can feel gratitude. They can feel approval, and they transmit those very simple feelings to the children.”

He added, “The reason this therapy works so well is that children with disabilities also have a very open spirit, and the horses sense it.”

The Rev. Richard Joyner, 62, pastor of the Conetoe Baptist Church in rural North Carolina, who created the Conetoe Family Life Center, will receive a $25,000 Purpose Prize on Tuesday. The center uses its 25-acre garden to improve the health of the congregation members and to increase the members’ high school graduation rates.

“It’s not easy getting people in the South away from fried chicken and sweet tea,” Pastor Joyner said.

In 2005, Pastor Joyner had faced too many funerals at his church of 300 congregants. In one year alone, 30 under the age of 32 had died. Most of the deaths were health-related, stemming from poor diet and no exercise, he said. His own sister and brother had died of heart attacks.

So he founded the center, which offers after-school and summer camp programs for children 5 to 18. The youths plan, plant and reap the produce, which, in turn, they peddle at farmers’ markets, roadside stands and to local restaurants. They also maintain beehives to produce and supply honey to low-income neighbors. The income they earn goes to school supplies and scholarships.

Getting involved with farming was not easy for Pastor Joyner. “I was a sharecropper’s son, and we experienced a lot of racism,” he said. “I never wanted to ever have anything to do with farming.”

But that changed. “The eyes of the youth have helped me to see the land in a different perspective,” he said. “Land is the soul. Farming gives these youths, who are struggling, the power to grow something that impacts the health of their family.”

As healthy eating and exercise have become routine, people in the community have lost weight, emergency room visits for primary health care have dropped by 40 percent, and the number of deaths has dwindled. The youth are enrolling in college and finding jobs.

As for Pastor Joyner, who runs five miles every other day and works in the garden, “After being a preacher for 25 years, I never thought I would be doing something other than trying to get somewhere for a vacation at this age.”

The other 2014 Purpose Prize winners who will receive $25,000 awards are:

■ Dr. Pamela Cantor, 66, a child psychiatrist who runs an organization called Turnaround for Children in New York City. Her group helps schools counter the effects of poverty on student learning, reaching tens of thousands of children in low-performing public schools.

■ Mauricio Lim Miller, 68, who founded the Family Independence Initiativein Oakland, Calif., which helps families in poverty. For example, families in the initiative have pooled their resources in 40 “lending circles” worth $1.5 million that have helped them pay down debt, provide funds for education and start new businesses.

■ Kate Williams, 72, who runs an employment program at LightHouse for the Blind and Visually Impaired in San Francisco, which helps the blind find jobs.

In addition to the six winners selected from a pool of nearly 800 nominees, 38 Purpose Prize fellows will be honored for contributions to their communities. The awards are sponsored by the Atlantic Philanthropies, the John Templeton Foundation, Symetra Financial Corporation, the MetLife Foundation and the Eisner Foundation.

Most of the winners tapped their own resources to start their endeavors, sometimes using credit cards or savings accounts — or, in one case, Social Security checks. Others raised money from personal connections.

“We encourage people who want to move the needle to consider what interests and passions they already have and review their skills — those are more transferable than they think,” Ms. MacDougall, Encore.org’s president, said.

“Seek out a group whose mission you admire and see if there’s a way to get involved by volunteering, joining a board or acting as a project adviser,” she said. “People who have organized things, been in marketing or sales or have managed people are in demand.”

The Purpose Prize recipients are free to use their jackpot any way they like. But don’t expect to see them buying new cars or taking trips to the Caribbean.

“My big reward is seeing these children improve,” Mr. Fletcher said. “I love watching a little boy with cerebral palsy, who can barely walk, trying to run to get to his pony.”

By KERRY HANNON OCT. 24, 2014