When we think about our lives and how we live each day, we have three concentric circles of our activities and behaviors. The innermost, smallest circle is our comfort zone, and most of us stay in there in the majority of our daily activities. The next circle is about double the size of the comfort zone, and that's our stretch zone. The majority of us spend about 5 percent of our time there on a daily basis. And then there's the huge, outermost circle - our "oh shit" zone. That's the place we avoid as much as possible, totally out of our control and beyond our imagination of our own capacity and drive.
When we take a leap like Kevin did, we stretch that comfort zone out a bit, but more importantly, we stretch our stretch zone out dramatically. What we thought we'd never do, suddenly becomes an option, a possibility.
Being in nature, really out there, beyond easy access to an escape route, we realize a) how little control we really have, and b) how little, in terms of "stuff" we need to survive. Being out there with no toilet, no toilet paper, and no access to prepared food leaves us with a complete understanding of exactly what is a necessity, and what is simply luxury.