Joel Peterson, chairman of JetBlue Airways, has spent a career leading teams, building businesses, and managing people at every level. Along the way, he's learned valuable lessons about the best ways to bring on new talent – as well as when and how to let people go. He also teaches at the Stanford Graduate School of Business and is the author of the book “Entrepreneurial Leadership: The Art of Launching New Ventures, Inspiring Others, and Running Stuff.”