Tommy Caldwell, one of the most famous rock climbers in the world, accomplished quite the impressive feat in 2015: he climbed The Dawn Wall, a 3,000-foot rock face that is part of El Capitan in California’s Yosemite National Park.

In an exclusive interview with uInterview, the 40-year-old Colorado native described his perilous experience scaling the the rock facade alongside his friend Kevin Jorgeson, as shown in the new documentary film The Dawn Wall. The pair of climbers were the first in the world to reach the top of The Dawn Wall.

“My dad was a mountain guide, so I grew up in the mountains,” Caldwell explained of his origins in the sport of rock climbing. “I started climbing when I was three and it has always been part of my life. I really wasn’t obsessed with it until I was a teenager and I started to understand how special the activity is.”

Caldwell also overcame an even more terrifying experience at a younger age. When he was 22, he was kidnapped by Islamic militants in Kyrgyzstan. The climber explained how being held hostage by  the rebels for six days helped shape who he is today.

“It was a like a life inflection point in terms of what led up to that and what has happened since,” Caldwell said. “[It was] six days of captivity where we lost 20 pounds in the high mountains, it was incredibly scary but a lot of really good things came out of it.”

He continued, “We suffered so much that we had to endure more than I really would have ever thought was humanly possible, and so I’ve always had this curiosity about that ever since. I saw the other side and so that really led to things like The Dawn Wall, which is primarily what the movie is about.”

Another scary incident that Caldwell suffered through? He accidentally cut off his left index finger when he was 23 — just months after being kidnapped in Kyrgyzstan — while “improperly” using a table saw to remodel his home in the Rocky Mountains of Colorado.

“It’s a big deal as a climber,” he said, laughing, of chopping off his finger. “It’s all about finger strength so I wondered if I was going to be able to continue to climb professionally. It made me realize how much I loved that life and how much I didn’t want to lose it. So I doubled down and got a lot better [at climbing].”

Caldwell stayed true to his word. He did not lose hope and his determination helped him scale El Capitan, which he described as “center-stage” in the sport of mountain climbing, as it sits in the heart of Yosemite. Caldwell revealed his father used to climb several routes on that part of the park while he sat at the base of it and socialized with other climbers.

Caldwell explained that there are two forms of climbing: aid climbing, a mechanical method that involves ladders, and free climbing, which is the more modern way of climbing. This method is similar to indoor rock climbing and is thus not always as secure, Caldwell stated.

“I think my story, in the nutshell, is about taking these hard experiences in life, turning them around and using them as fuel,” Caldwell observed.

The Dawn Wall is now in theaters and is available for streaming.