with a team of extreme athletes, dangling thousands of feet above the Earth with a lesson for everyone about facing your fears. We sent the correspondent afraid of heights, the brave ABC's lamb ma... See More
with a team of extreme athletes, dangling thousands of feet above the Earth with a lesson for everyone about facing your fears. We sent the correspondent afraid of heights, the brave ABC's lamb ma hassan. Reporter: We're floating 3,000 feet above space to witness an unprecedented stunt by a team of dare devils. You're afraid that you need to switch off your brain. Reporter: Two years in the making and a lifetime of training have come down to this -- they'll attempt to walk untethered from one hot air balloon from another, staring down danger and possible death is a way of life for these stuntmen. Something that I'm having trouble with. You see I am terrified of heights. I'm trying. Just look down into the valley. Reporter: No, no, no. Face your fear. Reporter: I can't. These dare devils admit they too have fear, they have learned to conquer it by facing risk, acknowledging their fear, making a plan and pushing off. Back in Spain, it was now or never for me to battle my fear. Oh, god, this is going to make me throw up. But, at last, I'll be crying. Just going up in the balloon makes me start to panic but their excitement as they attempted the impossible is so infectious that I surprised myself. You know those guys were saying you have to push yourself, face your fear, I have pushed myself like I have never pushed myself. Lama hassan. See it unfold on "Nightline" prime tomorrow night. When we come back here --
This transcript has been automatically generated and may not be 100% accurate.