Hemsworth on facing fears, ageing and return of Thor

Chris Hemsworth is best known as the hammer-wielding Norse god Thor in Marvels cinematic universe.

But now the Australian actor is trading superpowers for science, introspection and a new set of personal challenges, many of which are far scarier than battling fictional villains.

The 41-year-old is back for a second season of Limitless, which sees him confront some of his deepest fears as he explores how to live longer, healthier and better.

"The first season almost killed me," Hemsworth tells the BBC. "And I thought, never again."

In season one, Hemsworth tackled physical and mental challenges designed to delay ageing, including free diving, fasting, stress training and walking along a crane 900ft (275m) above the ground.

The actor says he chose to "torture" himself again because he had a burning curiosity to "ask bigger and deeper questions" about ageing and the meaning of life.

"It was exhausting but also profoundly rewarding," he says. "But now I do have more questions rather than answers!"

Season two takes a different path as Hemsworth continues to test himself, but not just physically. With the help of Ed Sheeran, he learns to play a musical instrument for the first time and, inspired by his childrens carefree risk-taking, he climbs a 600ft (185m) Alpine dam.

"Being thrust into unfamiliar environments where youre facing adversity or risk helps you understand how fragile life is and how quickly it can change," he says.

Hemsworth, whose brothers Liam and Luke are also famous actors, says he now takes nothing for granted and has learned to not "settle for the easy route as the greatest lessons come from the more challenging times".

One of the biggest challenges for the actor was in the first season of the National Geographic series when a genetic test revealed he carries two copies of the gene ApoE4, one from his mother and one from his father, making him between eight and 10 times more likely to develop Alzheimers than those without both copies of the gene.

"That warning sign was further motivation to take care of myself," Hemsworth explains.

"It also felt like a great opportunity to offer up education and a better understanding for people navigating it as Alzheimers is something a lot of people face."

While Hemsworth has become increasingly interested in how to live better, he says theres a fine line between healthy ageing and extreme biohacking.

Biohackers want to make their bodies and brains function better by "hacking" their biology.

"You want to live a longer and better life, but at what cost? You could have your exact routine, but theres no point doing all of that if youre isolated and lonely at home," says Hemsworth.

"Im going to put energy into health and wellness, but I also want to enjoy life."

This mindset puts him at odds with more extreme elements of the biohacking movement, which has gained attention through figures like tech entrepreneur Bryan Johnson.

Johnson, 47, has spent millions of dollars in a bid to slow down ageing - his regime, Project Blueprint, has seen him take numerous supplements a day, follow a strict diet and sleep routine, and undergo a plasma exchange.

Its an approach that Hemsworth finds intriguing but admits he has "no interest to explore".

"I like dancing in and out of those spaces," Hemsworth explains. "Sometimes I try one thing, then another, and different pieces of science resonate at different times in your life.

"If youre too boxed in with one way of thinking, you close the doors to other opportunities."

As well as reversing his biological age, Johnson also wants to crack the code on how to live forever.

But the Marvel star says no-one has figured out how to cheat death yet and he doesnt think anyone will, so "we have to embrace death".

"Suffering comes from denial of our inevitability of death - we all have an expiration date."

He adds: "If you were told you had 200 years guaranteed, youd become more complacent and reckless. The idea that life can be taken away at any second is a beautiful reminder to appreciate every moment."

He also explains that if humans could live forever then relationships with other people wouldnt be as important, and for Hemsworth, family appears to really matter.

The Thor actor lives in Byron Bay with his wife, actress Elsa Pataky, and their three children. Limitless touches on how his choices affect not just his own life, but those around him.

Part of what spurred him on to film a second series was "the great feedback from young kids, parents and grandparents" and realising that he was able to inspire others to challenge themselves.

Despite his status as a global action star, Hemsworth is very introspective and seems to be deeply driven in finding constant meaning and purpose to his life.

"This experience reminds me of what Im offering up and receiving," he says, adding that its important for him to always remember that "we dont survive and thrive on our own".

Alongside his lifelong quest to live better, Hemsworth is also thinking about what is next in his acting career.

Thor will return in Avengers: Doomsday, which is set to be released in the winter of 2026.

As to whether there will be another standalone film, the actor says: "I dont know, well have to see where this one goes as Im unpacking all of that now.

"Its something I certainly love and so well see what happens."

National Geographics Limitless: Live Better Now is available to stream on Disney+ from 15 August.

BBC News used AI to help write the summary at the top of this article. It was edited by BBC journalists. Find out more.