From 10 pm to 7 am, Henry Darby works the overnight shift stocking shelves at his local Walmart in South Carolina. When morning comes, he heads to his day job -- as principal of North Charleston High School. Every penny from his Walmart paycheck goes to his students, 90% of whom live below the poverty line. "I get a little emotional, because when you've got children you've heard are sleeping under a bridge, or a former student and her child sleeping in a car,” he said, with tears in his eyes. "These people need, and I wasn't going to say no. At my age ... we don't ask for money. We just don't. You just go ahead and do what you need to do." At Walmart, Darby never told his store manager about his day job. "Even before we knew, there was something special about him," store manager Cynthia Solomon said. "He's ready to help anybody," a student told the Today Show. "He's there when you least expect it, but when you need him the most," added another. Darby, not one to seek accolades, said, "I don't think I've done anything worthy of distinction to warrant the attention." He simply hopes his students (whom he calls his grandchildren) will pay it forward: "It's quite simple, simplistic: Just learn to help others. That is one of the greatest things that we could do in terms of human beings."