Since 2005, Monique Pool has helped rescue, rehabilitate and return hundreds of sloths back to the rainforest in her native Suriname. John Nowak/CNN
Pool's home serves as a temporary sanctuary for the mammals. John Nowak/CNN
For 23 years, Dr. Jim Withers has been treating the homeless in Pittsburgh, Pennsylvania -- under bridges, in alleys and along riverbanks. Krisanne Johnson/Getty Images for CNN
Since 1992, he and his group have reached more than 10,000 individuals and helped more than 1,200 of them transition into housing. Krisanne Johnson/Getty Images for CNN
Kim Carter helps women and their children break the cycle of homelessness in San Bernardino, California. KRISANNE JOHNSON for CNN
Since 2002, more than 800 women -- many who are formerly incarcerated -- have benefited from Carter's program. KRISANNE JOHNSON for CNN
Rev. Richard Joyner is leading his rural community in North Carolina to better health. David S. Holloway/CNN
More than 80 young people help Joyner plan, plant and harvest nearly 50,000 pounds of fresh food a year. David S. Holloway/CNN
Sean Gobin, a former U.S. Marine, helps support fellow combat veterans as they "walk off the war" on the Appalachian Trail and other long-distance hikes throughout the country. John Nowak/CNN
Ranging from two to six months, these journeys give veterans a chance to connect with nature and work through their issues while enjoying the camaraderie and support of other war veterans. John Nowak/CNN
Bhagwati Agrawal and his nonprofit created a rainwater harvesting system that provides clean water to six villages -- more than 10,000 people -- in India's driest region. Harsha Vadlamani/Getty Images for CNN
As a result, women no longer have to spend their days walking miles to fetch water. Girls can stay in school, and fewer people become sick. Harsha Vladlamani/Getty Images for CNN
Jody Farley-Berens and her group support single moms in Arizona who are battling cancer. John Nowak/CNN
Her group provides housecleaning, meals and financial aid to more than 300 parents and their children. John Nowak/CNN
Rochelle Ripley and her nonprofit provide healthcare and education opportunities to the Lakota people in South Dakota. David S. Holloway/CNN
Her nonprofit has delivered an estimated $9 million in services and goods to people living on the Cheyenne River Sioux Reservation. David S. Holloway/CNN
Dr. Daniel Ivankovich is an orthopedic surgeon who treats patients in Chicago's troubled neighborhoods, regardless of their ability to pay. JESSICA A. KOSCIELNIAK/Getty Images for CNN
Today, his group runs three clinics in Chicago, and he performs more than 600 surgeries a year. Jessica A. Koscielniak/Getty Images for CNN
After traveling in war-torn Nepal in 2006, Maggie Doyne changed her life's course to help children in the remote district of Surkhet. Vivek Singh/Getty Images for CNN
She and her group provide a home for nearly 50 children and a school that educates hundreds more. VIVEK SINGH/Getty Images for CNN