Nik Wallenda has walked across Niagara Falls on a 2-inch steel wire. He’s biked across a wire 135 feet above the ground. But he doesn’t think of himself as a daredevil.

Nic Wallenda talks about his walk across the Grand Canyon tonight at 8/9c

“I do consider what I do an art,” Wallenda said in a media conference call. “And, you know, I consider a daredevil more of somebody who says, you know, ‘I’m going to do something that’s never been done before but I haven’t trained for it either.  I’m just going to go do it and see what happens.'  Whereas ... I train and train and train and over-train for this. However, I’m not offended by those who call me a daredevil because I can understand their point as well.”

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Wallenda’s brain isn’t wired any differently, but people learn to deal with stress and fear in very different ways, said Jeff Wise, author of Extreme Fear: The Science of Your Mind in Danger.

“No fear is rational,” Wise said. “It doesn’t come from the prefrontal cortex; our brains process emotions in a parallel way. So (if I got on a high wire) I would immediately start getting heart palpitations, fall off and die. For him, he knows this material. Maybe for him it’s like walking down the sidewalk.”

Indeed, Wallenda says he’s been walking on wires so long (since he was 2, or even before he was born, if you count his mother walking on wires when she was 6 months pregnant) that it is second nature. Working as a police officer, he said, would scare him much more than walking across the Grand Canyon without a tether, which he will attempt on Sunday.

Wallenda recognizes that what he does is dangerous, and says much of his training is out of respect for that danger.

“For the last six months, I’ve sat out there and looked over the edge saying, OK, well, that is where I’m walking, that’s my view, and I’m going to make it to the other side,” he said. “For training I put up a cable that is the same or close to the same distance but lower to the ground but it’s the same tensions. And as I’m walking that cable I’m visualizing myself over the Grand Canyon at times.  And as I’m walking over the Grand Canyon I’ll be visualising myself back at training going, you did this. You did it in the winds, you did the distance, you’ve got the endurance, you’re going to be fine. It would be very easy to do the opposite and sit there and think how dangerous it is and I could fall and I could get killed and so on and so forth.”

Nik Wallenda strolls across the top of a ferris wheel. DCL

Many extreme athletes rely on similar mental training. And the adrenaline during a stunt or performance can help an athlete focus, Wise said.

“I think a lot of daredevils, their heart rates slow down once they get into that zone,” Wallenda said. “And I think the same is for me where it kind of just slows down and there are no problems in the world. If I’m in an argument with my wife that day or if I’m dealing with financial problems or health problems, all that goes away, no matter what. I’m on that wire and I’m going to make it to the other side and I don’t think about anything else.”

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Previous literature tended to vilify extreme sports athletes and label them as crazy, extreme risk takers, Brymer said. But serious athletes often spend years training to minimize the chances of things going wrong. And they understand that in addition to the technical skills, moving to the extreme level is about psychology.

“Bravery is when the conscious mind becomes aware you’re in a dangerous situation, but you trust your automatic self to do what needs to be done,” Wise said.

There is a balance between knowing your personal capabilities, the requirements of the task, and the environmental constraints. Successful extreme athletes and performers “know themselves well, understand the task and the environment and as a result, fear does not have to hold them back,” said psychologist Eric Brymer, who teaches at Queensland University of Technology in Australia and wrote his thesis about extreme athletes.

“The truth is there are really winds,” Wallenda said. “There is a large, large canyon 1,500 feet deep where I’m walking where those winds come around a corner and they change rapidly. So those are the things that are out of my control.  You know, everything you can control you can keep your mind at peace. Okay, I know I can walk on this cable. I know that I’ve done this distance. I know I have the endurance. I know I have the strength.”

But fear can also be transformative, Brymer said.

“Once I get on that wire it becomes surreal almost,” Wallenda said.  “I kind of get into my own world and into my own zone. And then I’m on a mission, and my mission is to make it safely to the other side.  And I get into a zone where that’s what I’m going to do. Nothing’s going to stop me.”

Nik Wallenda will attempt to cross part of the Grand Canyon on a tightrope, live on the Discovery Channel, on June 23 at 8 p.m. ET/5 p.m. PT.