"While anxiety is defined by uncertainty, human anxiety is greatly amplified by our ability to imagine the future, and our place in it, even a future that is physically impossible. With imagination we can ruminate over that yet to be experienced, possibly impossible scenario. We use this creative capacity to great advantage when we envision how to make our lives better, but we can just as easily put it to work in less productive ways — worrying excessively about the outcome of things. Some concern about outcomes is essential to success in meeting life’s challenges and opportunities. But at some point, most of us probably worry more than we need to. This raises the questions: How much fear and worry is too much? How do we know when we have skipped the line from normal fear and anxiety to a disorder?"