Back in 2002, Steve Stiliskinton was a software programmer for an investment firm, earning a comfortable six-figure salary. But he wasn’t happy. “I was frustrated with my corporate life,” he says. Part of the problem was his company’s investment strategy: “If they saw a profit in clear-cutting a forest or polluting a waterway, they’d invest in it,” he says. It was a jarring dissonance for the outdoorsman Stiliskinton. The day-to-day demands were also getting him down. “I sat at my desk every...