Teresa Amabile and Steven Kramer, authors of “The Progress Principle,” have been studying what they call inner work life—the confluence of emotions, perceptions, and motivations that occur continually throughout the workday. When inner work life is positive, people feel happy, have positive perceptions of their work and those they work with, and are highly motivated by the work itself. In their quest to find the forces that rule inner work life, the authors discovered that lower-level, local leaders —such as team leaders—can be surprisingly powerful.