The Hollywood star turned out on the red carpet in London's Leicester Square for the UK premiere of A Good Day to Die Hard, in which he reprises his role as tough New York police officer John McClane.
Willis first took on the iconic part in 1988 and, 25 years later, he's still going strong.
"I seldom think about the passage of time - I'm always surprised to hear that it's been 25 years. It's still fun to do," he said on Thursday night.
I still like making movies. They're fun to do, especially these Die Hard films.
Australian actor Jai Courtney is also loving the experience of playing Willis' on-screen son.
"Bruce is a lovely guy - we had a lot of fun making the movie. It was surreal and kind of strange, but a lot of fun," the 26-year-old said.
"You learn a lot working on a film like this."
He added: "You need a lot of trust too and we were able to work together in an organic fashion and had a lot of fun in the process. There was a lot of chemistry there."
A Good Day To Die Hard opens in cinemas on Valentine's Day, 14 February.