Dick Van Dyke, 98, says his secret to living a long life is going to the gym 3 times a week

• Dick Van Dyke, 98, credits regular exercise for his longevity.
• "Most people at 98 years old don't really feel like working out, and they seize up, you know?" he told ET.
• Experts say making simple lifestyle changes can significantly boost longevity.

Dick Van Dyke , 98, says regular exercise helps him live a long life.

In an interview with Entertainment Tonight alongside his wife, Arlene Silver, 52, the "Mary Poppins" actor spoke about staying active in body and spirit at his age.

"I've often tried to think, 'What did I do to live this long?' and I can't figure out," Van Dyke told ET. "The only thing is I've always exercised. We still go to the gym three days a week and work out."

Keeping active, he says, is "the secret" to longevity .

"Most people at 98 years old don't really feel like working out , and they seize up, you know? You get stiff, and I still, you know, move pretty well," he said. "And I think that must be the secret because I don't really watch my diet or anything. Stayed skinny. That helps."

It doesn't hurt that he also has a positive attitude toward life , Van Dyke said: "I was fortunate that I didn't grow up."

And Silver concurs.

"He's always happy and just positive," Silver told ET. "He's just the most joyful person."

According to the Centers for Disease Control, the average life expectancy in the US is 74.8 years for males and 80.2 years for females.

While immortality is still a subject of science fiction, there's been a growing interest in longevity and the idea of reversing one's "biological age."

Other antiaging trends — including IV treatments and red light therapy — are also gaining popularity.

However, longevity researchers say that even making simple changes to lifestyles can lead to a longer life.

Something as quick as incorporating a five-minute workout into your day or reaching out to two people you care about can help boost longevity , Dr. Kien Vuu, a physician specializing in antiaging and regenerative medicine, told BI previously.

A representative for Van Dyke declined BI's request for comment.