John Cena is in the final year of his in-ring career ... and once wrestling fans can't "see him" anymore, Booker T tells TMZ Sports he will be remembered as someone who took what he was given and turned it into an all-time career.

We caught up with the WWE Hall of Famer amid Cena's last dance ... and asked once the jorts are hung up for good, what lasting impact the legend will have on the sport.

He said that despite not being the best wrestler in the world, Cena "took what he had and made the best out of it, and took it all the way to the top."

"It's not out of disrespect or anything like that," T added. "I always talk to my students, I say, 'There's no wrong way of doing it long as you do it right.' And that's John Cena."

With it being the last go-around for Cena, the 59-year-old hasn't thought too much about any matches he hopes the 16-time World Champion wrestles in -- he only hopes he makes it out in one piece.

"That's gonna be for the fans to actually decide who they want John to see," he said. "Hopefully he have enough gas left in the tank to actually get it done."

While fans wait to see what the last hoorah brings for Cena, Booker is set to coach alongside Mickie James, Bubba Ray Dudley and the Undertaker in the company's new competition series, "WWE LFG (Legends and Future Greats.)" He tells us viewers will learn what it takes to make it in the business.