In this landmark book, the originator and pioneering researcher into Acceptance and Commitment Therapy (ACT) lays out the psychological flexibility skills that make it one of the most powerful approaches research has yet to offer. These skills have been shown to help even where other approaches have failed. Science shows that they are useful in virtually every area--mental health (anxiety, depression, substance abuse, eating disorders, PTSD); physical health (chronic pain, dealing with diabetes, facing cancer); social processes (relationship issues, prejudice, stigma, domestic violence); and performance (sports, business, diet, exercise). How does psychological flexibility help? We struggle because the problem-solving mind tells us to run from what causes us fear and hurt. But we hurt where we care. If we run from a sense of vulnerability, we must also run from what we care about. By learning how to liberate ourselves, we can live with meaning and purpose, along with our pain when there is pain.