I am 300 feet up a rock face, standing on two sloping footholds, my fingers curled around some small edges. Below me is the rope, my safety system, running down through equipment I've placed in cracks in the rock. The wall is steep, and my arms are tiring. From years of doing this, I know that staying in this position, in this place, means that I will eventually fall off. Tied to the other end of the rope is my friend Pete. It's his job to stop me if I fall. I start climbing again, focusing so intently that I have no consciousness of anything outside of my immediate vicinity. With exaggerated care, I place my feet and hands on the holds according to the sequence I've mentally rehearsed. Rock climbing is similar to playing chess, in terms of analyzing and planning. It's like gymnastics, in terms of the physical strength and coordination required. And it's like dancing, in terms of the grace of movement. Fundamentally, though, it's about commitment and a belief in your ability to succeed. And so I try, in my flatland life, to remember that the apprehension I feel when trying something new is a natural physiological reaction to uncertainty. And I remind myself that mostly it's the fear of failure, of embarrassment that stops me.