John Cena Confronts His Final WrestleMania

John Cena knew his time was up.

For more than 20 years, Cena was a symbol of excellence and inevitability in professional wrestling. Cast as the ultimate good-guy character in World Wrestling Entertainment, he was Superman in jorts — a 16-time world champion and perhaps the last of the monocultural, crossover stars, following the likes of Hulk Hogan, “Stone Cold” Steve Austin and the Rock.

But even in the world of sports entertainment, Superman doesn’t live forever. And Cena remembered a promise he had made to the audience: When I get a step slow, I’m out.

“And I’m a step slow,” he said.

The realization kicked in a couple of years ago. Cena was down 15 pounds from his ideal in-ring weight. He couldn’t lift as much. He no longer looked like Mark Wahlberg ate Mark Wahlberg. It was time.

“It is not from lack of trying. I’m just [expletive] old,” said Cena, who turns 48 this month. “I’ve never been the best wrestler out there — I know who I am and my capabilities. So, when I can feel myself getting a little slower, it’s time to go.”

Cena says this inside a trailer on a movie set one snowy Sunday morning in early April near Cierne, a small Slovakian village near the border of Poland and the Czech Republic. He is roughly 6,000 miles away from Las Vegas, where on Sunday he will face Cody Rhodes in the main event at WrestleMania, Cena’s 17th and final time participating in W.W.E.’s flagship spectacle. A victory would make him the most decorated champion in the history of professional wrestling. But a set like this has become Cena’s work space as much as the squared circle over the years. He’s here filming “Matchbox,” the latest toy-brand-comes-to-life franchise with blockbuster ambitions, and Cena is the top-billed star. He makes sense in that role because even for people who don’t know an Attitude Adjustment from a People’s Elbow, Cena has become a household name.

He’s been in action franchises (as Vin Diesel’s brother in the “Fast and Furious” movies), sex comedies (a buff boyfriend who is awful at dirty talk in “Trainwreck”) and world-conquering blockbusters (Mermaid Ken in “Barbie”). He’s a top-selling rap artist (that’s him on the mic for his enduring entrance music) and has made memorable appearances on “Saturday Night Live.”