Renowned psychologist Walter Mischel, designer of the famous Marshmallow Test, explains what self-control is and how to master it. A child is presented with a marshmallow and given a choice: Eat this one now, or wait and enjoy two later. What will she do? And what are the implications for her behavior later in life? The world's leading expert on self-control, Walter Mischel has proven that the ability to delay gratification is critical for a successful life, predicting higher SAT scores, better social and cognitive functioning, a healthier lifestyle and a greater sense of self-worth. But is willpower prewired, or can it be taught?