10 words stuck with Mr. Sonnier for 15 years. They turned him from janitor to principal.

There's that person in life that says something to you and it stays with you forever.

For Joseph "Gabe" Sonnier, who was the janitor at Port Barre Elementary School, those words came one day in 1985. The principal of the school pulled him aside.

"I'd rather see you grading papers than picking them up," principal Wesley Jones had said to him, as Sonnier recalled to CBS.

He'd never forget those words. Sonnier continued on with his job as the loving and respected janitor that he was, but 15 years later, he revisited what Jones had said.

All GIFs via "CBS Sunday Morning."

He decided to go for it.

Sonnier decided to go back to school and become a teacher. At 39 years old. All while still working full-time as Port Barre Elementary's janitor.

"I would come to work at like five in the morning and leave at seven and go to school all day, and then come back and finish up my eight hours of work here, and then go home and do homework," he told Fox2Now.

Oof. That's quite a day ... every day. But the hard work paid off in a big way.

He got his Bachelor's degree and became a teacher in one of the very classrooms he used to clean.

And when he later got his master's degree? Well, the best thing happened. Everything came full circle.

Port Barre Elementary announced its new principal in November 2013, and it was their very own Mr. Sonnier.

Hooray, Mr. Sonnier!

Although that definitely didn't stop him from cleaning his own office.

Mr. Sonnier's story just goes to show that if you've got a goal, go for it. And if you believe in someone's potential — tell them.

"Don't let your situation that you're in now define what you're going to become later," he said. "I always tell them it's not where you start, it's how you finish."

I'd go on to add, it's also who you meet and are inspired by along the way.

Hear more about the incredible Mr. Sonnier in this "CBS Sunday Morning" feature: