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."
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.