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 behaviour later in life? Walter Mischel’s now iconic ‘marshmallow test’, one of the most famous experiments in the history of psychology, proved that the ability to delay gratification is critical to living a successful and fulfilling life. Now, Dr Mischel draws on decades of compelling research and life examples to explore further the nature of willpower, identifying the cognitive skills and mental mechanisms that enable it and showing how these can be applied to challenges in everyday life, from weight control to quitting smoking, overcoming heartbreak, making major decisions and planning for retirement.