Alain Robert and Jeb Corliss are two men who've never met, yet they share many of the same experiences. They're both risk takers driven by their fears.
Corliss, 34, uses a flying squirrel-style wing-suit to travel at speeds of up to 300 mph and steer through the air during freefall.
"If you want to do something spectacular, something special, you have to be willing to take really unique risks," said Corliss.
Corliss described his childhood as unhappy and isolated. By his teens, he said, he was suicidal.
"I didn't really care, nothing mattered to me," Corliss said. "And all I know is that feeling made me want to do things that were really, really dangerous."
Base jumping -- freefalling from high structures -- became his passion, and he jumped from iconic landmarks across the globe.
"In my search for death I really did find my life," Corliss said.
Flying Man's Next Exploit: Matterhorn
Forever pushing the limits, Corliss moved on to wing-suit flying, which allowed him to fulfill his childhood dream.
"I was about 5 years old and I was watching these birds, and I remember seeing them open their wings and start to fly," said Corliss. "And I remember going, you know what, when I get older I'm going to do that."
In 2007, Corliss flew past the Christ the Redeemer Statue in Brazil. He describes that flight as amazing but felt he wasn't close enough to anything -- so he set his sights on the Matterhorn in Switzerland.
Now he trains constantly to avoid missteps, like the one he had in Italy while training to fly off the Matterhorn.
His parachute got caught on some branches during his descent, and he broke his hand in two places. He was still determined to get to the Matterhorn in the Alps.
Last year, with his left hand broken, and armed with his trademark cameras that document all his flights, Corliss jumped out of a helicopter at 16,000 feet. He flew at speeds of almost 200 mph, in the coldest temperatures he's ever flown.
How does the suit enable him to fly like a bird? It has vents that fill with air as he falls, inflating his "wings" and allowing him to slide against the air.
At one point on the way down the mountain, Corliss felt he was too close to the mountain, he said, but courage led the way down.
"It's all bonus time as far as I'm concerned," he said. "I've already lived my life 10 times over. If I died tomorrow doing what I love, I don't want anyone to cry for me. Everyone should throw a celebration, because I died doing what I loved."
'French Spiderman' Aims High
Alain Robert is also in the business of challenging himself to challenge his fears. At 47, Robert is known as the French Spiderman.
He lives in a small town in southern France but has traveled all around the world, scaling the tallest buildings he can reach.
For Robert, being daring is funny because as a kid, he said, he didn't have a lot of self-confidence.
Robert found his calling at age 11. Rock climbing with the Boy Scouts was the spark, but forgetting his keys at home brought it to another level.
"I left them in my house and my parents were both working, so I decided that I was going to climb my parents' building, and I did it successfully," said Robert.
To date, Robert has climbed more than 70 skyscrapers around the world, including Shanghai's tallest building, the Jin Mao Tower, in 2007. That ascent was caught on tape.
As Robert put on a Spiderman costume, he described being very nervous but having just one goal -- to scale the building without using a harness or safety net. His only aid: climbing shoes.
"I need to be very, very fast, this is nearly like a race," said Robert.
Robert needed to be fast to dodge security at the 88-story skyscraper. Quickly the police converged and a crowd gathered, cheering him on, but he said the attention doesn't affect him.
"I love, you know, kicking the ass of the society, you know something illegal," Robert said. "Most people in a way they are dreaming of doing something like this, but they don't have the guts to do it."
Following the illegal climb, Robert was arrested and spent five days in jail before he was deported. He was banned from China for five years, but the ban was lifted later that year, and he was invited back to scale a mountain.
'French Spiderman' at Home
Today, when he's not climbing, Robert is at home with his wife and sons, who, he said, understand what he does.
"I ask him are you well prepared, are you training enough," said his wife. "I accept him the way he is."
He drew a contrast between managed and unmanaged risks. He manages his risks, he said -- but he yells at his wife for smoking, which he calls an unmanaged risk.
"This is not a managed risk when you smoke," Robert said. "When you smoke you are building your own tomb. When I climb, if you're mentally and physically prepared, you minimize the risk."
To increase his odds of survival, Robert trains constantly. There's even a rock climbing ceiling in his bedroom. Although he said it is tiring, Robert has no thoughts of retirement.
"For me, climbing is as important as eating, breathing, sleeping," Robert said. "I don't want to change my life."
And conquering his fear of heights is like a reward for Robert.
"I won't say I am dominating heights, but at least I am capable to dominate my fear," said Robert.