What makes a feeling bad?

Life is not easy. It is full of ups and downs. Most of us do our best to focus on the ups and push through the downs as quickly as possible - but Krista K. Thomason, an associate professor of philosophy at Swarthmore College, says in her new book, "Dancing with the Devil: Why Bad Feelings Make Life Good", that maybe we should re-examine that mindset. We talk with Thomason about the book and why bad and negative feelings are important.