NFL legend Emmitt Smith got his first job at 12 working as 'the utility guy' at a nursing home

Retired NFL star Emmitt Smith
CHRIS WILKINS | Getty Images

When Emmitt Smith was 12, he really wanted a pair of Jordache jeans. When he asked his mom if she'd buy them, she said she couldn't afford to, but recommended he start working and pay for them himself.

"So I got my first job at Magnolia Nursing Home, mopping floors, taking out the elderly people's stuff, making up beds, trimming the hedges, raking the yard," the former NFL superstar told Maverick Carter on an episode of Uninterrupted's "Kneading Dough."

"I was the utility guy," added Smith, whose mom also worked at the nursing home. His dad worked as a city bus driver.

He saved everything he earned that summer, but he didn't end up buying the jeans. "One of the most beautiful things I learned through that whole process was, my mom asked me to borrow some money — and I was able to give it to her," recalls Smith. "I loaned her a couple hundred dollars, and it felt good to give it to her. It helped me understand that, wow, that's a good feeling."

Less than a decade later, Smith was drafted by the Dallas Cowboys and at 20 started earning a much larger paycheck: His signing bonus made him a millionaire overnight. He went on to win three Super Bowls, earn millions more and become the highest-paid running back at the time, after signing a four-year, $13.6 million deal in 1993.

While Smith is the first to admit that he made a few "'youthful' financial decisions," including buying a $100,000 convertible his rookie year, the Hall of Famer also picked up some valuable lessons during his lucrative, 15-season career.

It was Dallas Cowboys owner Jerry Jones who gave him the best money advice. "He taught me about finances with a simple statement," Smith recalled in an interview with CNBC. "He always said, 'Have a big front door and a small back door. Take in as much as you can and spend as little as you can.'"

Have a big front door and a small back door. Take in as much as you can, and spend as little as you can.
Jerry Jones
Dallas Cowboys owner

Today, Smith is able to give on a much bigger scale than the couple hundred dollars he gave to his mom when he was 12. He started a foundation with his wife — Pat & Emmitt Smith Charities — that has been providing resources and educational experiences for under-served kids since they founded it in 2002.

As for the "loan" that Smith gave his mom, "I never got it back," he told Carter, laughing. Moms "pay back in other ways," he added.

Don't miss: Emmitt Smith says the best money advice he ever got came from Cowboys owner Jerry Jones

Like this story? Subscribe to CNBC Make It on YouTube!

This NFL starting quarterback drives a dented van he bought from his grandma for $5,000