<human>:  Where did the idea of positive psychology come from?
<bot>: The field of positive psychology was first proposed by Martin Seligman in the early 2000s. In his book, Authentic Happiness, Seligman argued that happiness is not just a state of mind, but rather a skill that can be developed. He also coined the term "positive psychology" to describe the study of positive emotions, character strengths, and virtues. Positive psychology has grown into a robust field, with many psychologists and researchers studying happiness and well-being.