Mason Wartman opened Rosa's Fresh Pizza in Philadelphia as an entrepreneurial endeavor following a few years of working on Wall Street. He intended to make money, but ended up making a difference.

Three months after opening, a customer came in and left a dollar to buy a slice for a homeless person, and Mason turned it into a pay-it-forward pizza system whereby people can buy slices for the homeless. He's since served over 8,500 slices to the homeless, and serves about 30-40 homeless people daily.

Ellen invited Mason to the show this week to share his story, and to help him generate more business.

"I'm just really flattered that she thought my story was cool," Mason said backstage after the show. "It's definitely a nice way to break up the week – that's for sure."

After the pay-it-forward system took off, Mason's walls became covered in post-it notes representing customer gifts, and he's aiming to eventually open up more shops around the city to continue his program. Ellen gave Mason a new sign for his storefront window and a $10,000 check from Shutterfly to cover pizza for those in need.

"That definitely helps us keep the lights on, and that's 10,000 more slices for homeless people," Mason noted. "Hopefully they'll use it to better their lives."

While one piece of pizza may not seem like much, it does make an impact to those who have nothing at all. Many of Mason's customers panhandle for food, and that slice can be their only meal of the day.

"The post-its that mean the most to me are the ones homeless people buy when they're no longer homeless," Mason says. "A couple months ago, the first homeless guy that really got out of his situation, a guy named Marty – he came in and told me that by eating at my shop a couple days a week, he was able to save up enough money for some new clothes and a haircut. He was able to look professional in a job interview, and he got the job."

See our full interview with Mason above!