Rod Stewart Says He's in the Best Shape of His Life at 77 -- Here's His Secret (Exclusive)

Forever young! Rod Stewart is returning to Las Vegas this week for his residency engagement, and the celebrated singer is opening up to ET about some changes to the new show and how he's managed to get healthier than he's ever been at 77.

Stewart -- who is also gearing up to kick off a new tour -- explained to ET's Matt Cohen, "I have a trainer who's always with me, [getting me] running, cycling, everything."

"I'm actually in better shape now than I've ever been," Stewart shared. "I played a lot of football when I was young, up until my 60s, really, but it all caught up to me and I had to have a new knee."

"So this knee is steel," Stewart added, nodding to his rebuilt knee. "And the ankle, so I can run really fast now."

With his residency show, Rod Stewart: The Hits, returning May 13 to The Colosseum at Caesars Palace, Stewart is more ready than ever to deliver some epic performances.

"I always have to give people what they want, so they want to hear the songs that made me famous. But we've added a few [new songs] and a couple of songs by other people," said Stewart, who revealed that he'll be performing covers of Blondie's "Call Me" and "Hot Stuff" by Donna Summer.

Stewart also teased his upcoming North American tour, kicking off June 10 at Rogers Arena in Vancouver, which he called "a very colorful and sexy show."

After a career spanning six decades, Stewart is still rocking hard and delighting audiences, and the singer says it's simply "because I love it."

"It's part of who I am. In fact, it is who I am," Stewart said. "This is what the good lord put me on this earth to do, nothing else."

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