Ashton Kutcher has been open about the health issues he's battled for the past few years, but now he's revealing how those struggles led him to pushing himself at the South Pole.

"I had a weird autoimmune disorder three years ago," he shared on "The Late Late Show with James Corden."

"So last year, I was like, 'I am just going to push myself to the end of my physical capacity in every form.'"

As part of this mission, he said, "I went to the South Pole, I ran a marathon, I went ‘Running Wild with Bear Grylls.’ I was just going to push it as far as I can just to get the self-confidence that I'm fully back, which I am."

During the trip, Kutcher climbed a mountain and was given the opportunity to name it – and his mind instantly went to his wife Mila Kunis.

He explained that he went on the hike with a man he'd met on the trip.

Kutcher said "We get to the top and he said, 'You're the first person that has ever climbed this mountain. You get to name it.' I was like, 'Okay really? It's Mount Mila.'"

Although it was a sweet gesture, he said the man told him "No, no, it's bad luck to name it after another person, so don't do that."

Instead, he chose to name the mountain the Russian word for "awesome," which was another way to honor Kunis, who was born in Ukraine with her first language being Russian.

He called the whole experience "wild."

ASHTON KUTCHER REVEALS HE WAS ‘DRUNK’ THE FIRST TIME HE TOLD MILA KUNIS HE LOVED HER

Kutcher suffered from vasculitis, an inflammation of the blood vessels. For him, that meant starting to suddenly lose his sight and hearing a few years ago.

In an interview for "The Checkup with Dr. David Agus" in December, he talked more about how vasculitis motivated him to push himself physically.

"Part of it is, this sort of mental thing I have around achieving a full comeback from waking up in the hospital," he said. "I was unable to walk, and I was like ‘Wait a second. If I can go from not being able to walk to running a marathon in a three-year span, then I can sort of just let that be a part of the past' and be like, ‘I’m good. I'm back.'"

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As for Kunis' assistance in his recovery, she explained in an interview last year, "I don't think you have time to sit down and talk, you kinda just power through. You go and deal with whatever health issue comes your way, but you still got kids, you still got a family, you have to live life."

She continued, "I think that we are so fortunate to have one another, but as far as sitting there and incessantly talking about things, no. You gotta do."