William Shatner shares tip for staying youthful at 93

"Star Trek" actor William Shatner, who celebrated his 93rd birthday Friday, feels as young as ever.

Shatner's secret to remaining youthful in his 90s is: "Just staying engaged in life, to stay curious. But the luck has a lot to do with it in your health."

"Your life's energy, the soul energy of your body is a product of health," he told People. "If you're sick, you can't be energetic. You're dying. So my luck has been, I've been healthy all my life."

WILLIAM SHATNER SHARES HIS BIGGEST REGRET FROM HOLLYWOOD CAREER: ‘I FAILED HORRIBLY’

The actor, who starred in the original "Star Trek" show from 1966 to 1969, prides himself on still being "energetic."

He told People at the premiere of his documentary, titled "You Can Call Me Bill," Thursday that he largely credits that positive outlook to his "wife," Elizabeth Martin.

Shatner was married to Martin from 2001 to 2020, when their divorce was finalized. Reconciliation rumors began to spread after the former couple attended the Living Legends of Aviation Awards together in January 2023.

He told the outlet that he doesn't tend to take birthdays too seriously and prefers a laid-back celebration.

"Well, birthdays are purportedly a big day. I suppose there's a reason for somebody outside to celebrate, ‘Oh my God, 93,’" he said, adding, "I'm not glorying in it."

Prior to his big birthday, Shatner shared his biggest regret from his long Hollywood career.

Speaking candidly about his 1989 film, "Star Trek V: The Final Frontier," Shatner implied that the project was doomed from the start. He reprised the role of Capt. James T. Kirk in the film, which he originally played in the TV series.

"I wish that I’d had the backing and the courage to do the things I felt I needed to do. My concept was, "'Star Trek' goes in search of God," and management said, ‘Well, who’s God? We’ll alienate the nonbeliever, so, no, we can’t do God,’" he explained to The Hollywood Reporter.

"And then somebody said, ‘What about an alien who thinks they’re God?’ Then it was a series of my inabilities to deal with the management and the budget," he said of the subsequent steps to making the film, in which he served as director. "I failed. In my mind, I failed horribly." 

"When I’m asked, ‘What do you regret the most?’ I regret not being equipped emotionally to deal with a large motion picture. So in the absence of my power, the power vacuum filled with people that didn’t make the decisions I would’ve made," he lamented.

When it was released, the "Star Trek" film was criticized for its lack of execution and being an overall disappointment. Shatner noted that he takes all the blame, even if people question his budget or the support he had in hindsight.

"It is on me," he reiterated, giving an example of mismanaging his $30 million budget. "[In the final scene] I wanted granite [rock creatures] to explode out of the mountain. The special effects guy said, ‘I can build you a suit that’s on fire and smoke comes out.’ I said, ‘Great, how much will that cost?’ They said, ‘$250,000 a suit.’ ‘Can you make 10 suits?’ He said, ‘Yeah.’" 

"That’s $2.5 million. You’ve got a $30 million budget. You sure you want to spend [it on that]?" he remembered thinking. "Those are the practical decisions."

Shatner's plan famously didn't materialize, due to mechanical issues toward the end of filming.

Despite the memorable bump in the road, Shatner has remained successful both in front of and behind the camera. 

"It's luck. It's the luck of being healthy," he told Fox News Digital in June of his longevity in the entertainment industry. "I think that's the first thing … I've had things happen, but nothing debilitating over a period of time. So having the life force within me, is probably, mostly, what it's all about."

Fox News Digital's Caroline Thayer contributed to this report.