Chris Hemsworth has openly revealed that he was initially reluctant to return for another series of the documentary show Limitless, which explores extreme health and wellbeing challenges.

The second series of Limitless launched on Disney+ on Friday, August 15, featuring three episodes that examine various approaches to help individuals enhance their quality of life.

Supported by specialist guidance, the actor Chris Hemsworth faces different trials centred on mental capacity, endurance and danger - all designed to promote better living.

The concept differs slightly from the inaugural series, which concentrated on methods for extending lifespan, with the 42 year old undertaking some extraordinary experiments.

These challenges involved scaling a 100ft rope suspended from a cable, maintaining balance on a construction beam high above ground and plunging into icy Arctic waters.

Therefore, it's perhaps understandable why the star was initially hesitant about returning to the Limitless series for a second run.

Speaking candidly at the Q&A session, he quipped: "I didn't initially.

"The first season almost killed me emotionally and physically, whether that's by design or intention.

"But in the aftermath after the show had aired, I was at my kids' school and their friends were coming up and talking about what they'd received from the show or their parents and grandparents.

"The sort of spectrum of age groups and demographics and so on, from different areas and countries, all around the world who had received some sort of knowledge and new direction or path to pursue to [achieve] the best version of themselves.

"So we discussed if we would do a second season, what would we tackle, what could be expanded on that had been touched upon in the first one."

Reflecting on his accomplishments three years prior, the Australian celebrity went on: "In the first season, I was very much a guinea pig.

"I was thrown into a situation with very little knowledge about what I was doing.

"This was more experimental journalism I guess. I had more agency in the production and creation of where we were going to head.

"It was personal to me in different ways and things I want to investigate.

"And throughout the second season I kept asking the same question, 'What the hell am I doing?'"

Limitless season two premieres on Friday, August 15, on Disney+.