Within the field of positive psychology, particularly informed by the work of the late researcher Christopher Peterson of the University of Michigan, optimism is defined as the expectation that the future will be socially desirable, good, and pleasurable. Research suggests that optimistic people enjoy concrete, long-term benefits to their health and happiness. However, Peterson has identified some downsides to optimism, if taken to extremes. "Optimism in the form of wishful thinking," he writes, "can distract people from making concrete plans about how to attain goals." And "unrelenting...