Emotions and thoughts relate to psychological well being, but the common conception that difficult thoughts and feelings are central to poor functioning is not correct. The ability to feel and think a wider range of things and to relate to emotional and cognitive content in a more open and flexible way is more key to psychological health than the absence of difficult content. In this paper I will show how modern evolution science and contextual behavioral psychology point to the importance of psychological flexibility to a wide range of areas of human functioning. Psychological flexibility can be learned and not just in the clinic. I will describe the core features of psychological flexibility, its benefits, and how we can learn these skills.