FORTUNE — Greg Carr was on the road to an early retirement 14 years ago. At age 40, the Idaho native sold his voicemail system company for $843 million. He could have followed the path of other tech entrepreneurs and become an angel investor, started yet another company — or simply kicked back. But Carr had something else in mind.

“I was not going to just stop working at age 40 and sit around for 40 or 50 years with a bunch of money in the bank and play golf and write a check every so often to some charity,” he says. “I wouldn’t feel like I was doing anything meaningful for the world.”

In 2004, Carr traveled to Mozambique. One of the poorest countries in the world, he says he immediately noticed how rich the country was with cultural capital. Covered with beautiful beaches, forests, and rivers, Mozambique had the makings of a booming tourist industry, he says. Rather than see a country riddled with problems, Carr’s business mind saw one rife with opportunity.

Gorongosa National Park, a 1,500-square-mile park in central Mozambique, stood out. Dubbed by tourists as ”the place where Noah left his ark,” Gorongosa was historically the home to thousands of wild animals including zebras, waterbucks, and antelopes. Yet years of civil war and a persistent poaching community took away about 95% of the species, Carr says. An unbalanced and nearly destroyed ecosystem was left behind. With no solution in sight to restore the park, Carr jumped at the chance to put together a team to solve the problem.

The following year, Carr formed the non-profit Gorongosa Restoration Project and established a public-private partnership with the Mozambique government to restore the park. In 2008, Carr committed $30 million of his fortune to the cause, and his non-profit signed a 20-year agreement to jointly manage Gorongosa with government officials. The park’s second largest donor is  the United States Agency for International Development which has contributed more than $1 million each year since 2007.

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Carr’s goals were ambitious. He not only wanted to revive the animal and plant populations within the park, but to support the African communities surrounding the nature reserve as well. A false dichotomy exists in environmental work, he says, and most people assume that nature preservation stifles economic development. In Mozambique, the opposite is very much the case. By preserving the park and its wildlife, Carr simultaneously could create income and jobs for community members.

“If you want to do the most good in the world, go to the place you are most needed,” he says. “We had to repair this damaged ecosystem so it could be ready not just for tourism again, but so it could restore the national economy.”

In addition to creating animal sanctuaries to cultivate the wildlife population in the park, Carr built elementary schools, water sources, and health clinics in nearby communities. His team also created a luxury safari camp within Gorongosa to employ more Mozambicans. His non-profit commits about 20% of the revenue from the park’s tourism fees to the 15 communities surrounding the park, he says.

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In just five years, Carr’s team has successfully restored as much as 40% of the animal population within the park. More than 400 jobs have been created within the park, and thousands of farmers benefit from preservation of the floodplains as well.

“If the park benefits the people, they are going to want to benefit the park,” Carr says. “The big challenge right now is simultaneously protecting the planet as people grow in numbers and consume more.”

Gorongosa has transformed into such a thriving ecosystem that scientists and researchers are flocking to the park to study. Yesterday, Carr opened the park’s first biodiversity research facility. Named after Harvard professor and leading biodiversity researcher Edward O. Wilson, the center will serve as an educational hub to train the next generation of Mozambican scientists in the park. Wilson has traveled to Gorongosa three times to conduct research as well as to educate Mozambicans about the thousands of specific within the park.

Carr shows no signs of slowing down his active commitment to Gorongosa anytime soon. This year, Carr is putting together a program that will help farmers in the areas surrounding the park earn better yields from their crops. It is likely that he will match his initial $30 million commitment to the park again sometime in the future, he added.

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As for the dramatic turn Carr’s life took in the second act of his career, he says he wouldn’t have had in any other way.

“How could I have possibly have been as satisfied with a second computer company that more or less looked like the first one? I’m building a national park in Africa,” says Carr. “It’s not even a contest.”

WORDS OF WISDOM

Advice for retirees considering a move from corporate to non-profit

“Recognize that non-profit organizations need your business skills. More than your check, they need your business management.”

What he wishes he knew before the switch

“When I started my for-profit company, even thought I was very young, I was very rigorous. For whatever reason, I was less rigorous in a way [with Gorongosa] because I was older and had money, and I was going out to do a good thing. I realized that mistake pretty quickly, and now I am very rigorous.”

Biggest challenge

“If you choose to do something in the developing world, the biggest challenge is that everything will be harder. In Africa, everything takes longer. You don’t have the infrastructure to draw upon … so you are going to have to work harder.”

Biggest reward

“That extra challenge makes the work even more rewarding.”

Next is a series of articles that looks at executives’ efforts to use their talents and skills to enrich or support the lives of others and upon retirement from professional life.