Conservationist and self-described "planetwalker," John Francis explains what he means by sustainability. "While loss of habitat and species, pollution, and what we typically think of as environmental problems remain important issues for me, after walking across America listening and studying the environment for 17 years I realize that people are part of the environment. If this is true, then our first opportunity to treat the environment sustainably, or even understand what sustainability is, can be found in our relationships with ourselves and each other."