"A Wookiee survives over a period of time," says Peter Mayhew

While the returning characters from the original Star Wars trilogy are showing the passage of 30+ years, Chewbacca looks like not a day has passed in Star Wars: The Force Awakens. The fur still has that dark, youthful, bouncy shine, even as BFF Han Solo has gotten snowy up top.

What’s Chewie’s secret? “A Wookiee survives over a period of time,” says Peter Mayhew, the 7-foot-3 actor inside that Wookiee suit, in the new PEOPLE Star Wars special issue. “Chewie’s a baby compared to other Wookiees even though he’s over 100 years old.”

See exclusive photos, get a first look at new characters and learn more secrets from the cast and crew of Star Wars: The Force Awakens in PEOPLE’s Star Wars collector’s edition, on newsstands now. And for more exclusive Star Wars news, come back to PEOPLE.com every day until it hits theaters Dec. 18

Also helping is that the Force Awakens suit is a replica from the first series. “They took the original costume and remade it exactly the same,” Mayhew says. “The mask had a little bit of modification, but nothing that we couldn’t modify because we were using the guys who originally made it.”

The intervening years have been tougher, though, on Mayhew, now 71. He had both his knees replaced in 2013 after being confined to a wheelchair. When director J.J. Abrams approached him to reprise the role of Chewbacca, Mayhew says, “I explained I could only do so much. He said, ‘Don’t worry. We’ll find someone big [to be a stand-in] and make you as comfortable as possible. What we need you for are the close-ups.'”

Working again alongside Harrison Ford, the classic rapport came roaring back. “On-set, Harrison knocked on my trailer door, gave me a great big hug and said, ‘Hey, buddy! You’ve got to get back in the old suit again?'” Mayhew recalls. “It was wonderful.”

The actors also easily slipped back into their method for shooting Han-and-Chewie scenes, with Mayhew reading the lines in English (the Wookiee sounds were added later) and Ford casually responding. “It works very, very well,” Mayhew says, including with new cast members John Boyega and Daisy Ridley.

As for Chewbacca’s fate in Force Awakens, Mayhew is very eager to discuss the story, but he can’t. “You know, there’s a certain piece of paper that’s been signed,” he says. “You’ll have to wait and see.”