ABC News March 28, 2016

Grandson Gives Grandparents the Surprise of a Lifetime

WATCH: Grandson's Surprise of a Lifetime for Grandparents

Stefun Darts was preparing for weeks for a special surprise for his grandparents. On March 20, the 24-year-old gathered his family members together at his grandparents’ home in Houston, Texas, to present his grandparents with a check for $15,000 -- the amount of money needed for them to pay off their mortgage.

“The surprise on my parents’ faces was unbelievable,” Travelle Roberts, Stefun's uncle, told ABC News today.

Family members started tearing up during the emotional moment, including Stefun's mother, Stefanie Wyatt, 40. “I started crying. It was so sweet,” she said.

Cecil and Marilyn Roberts welcomed their grandson into their home when he was in first grade. When Stefun was in the second grade, he made a promise that he would pay off his grandparents’ mortgage.

“I couldn't stand you going to work at night, some nights I didn't even sleep knowing it shouldn't be like this,” Stefun wrote on his Facebook timeline.

For the past six years, Stefun was working nonstop and was frugal with his spending to make sure he could keep his promise. He worked odd jobs -- everything from working as a cook in Pizza Hut to answering phones for a customer service company. He tried not to spend a lot of money on food, and never smoked or drank to save as much money as possible.

Besides working full time, he is also a full-time student at San Jacinto College and the founder of the non-profit organization Caring Heart Youth Foundation. “I sleep around four or five hours a night,” he said, adding that he is “always giving back to help."

Not only did Stefun pay off his grandparents' mortgage, he also paid for a trip for the two of them to the Bahamas - a complete surprise to other family members.

“I definitely didn’t know about that,” Wyatt said.

She added that Stefun goes out of his way to help others. "It is second nature to him,” she said.

“It was a dream to see them happy,” Stefun said. "It’s something that can’t be explained, it can only be felt.”