There are parallels between filmmaking and climbing mountains just in terms of the commitment it requires, absolute devotion, and the belief that you are going to make a film and that the film is going to be OK, as well as the risks you have to take. You are never going to climb anything great if you don't take risks.
Right on through today, my lungs and stamina are my engine. I'm not nearly the strongest guy or the most flexible, but I can definitely sustain pace on the mountain.