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."