This is strong, informative information about the cause-effect relationship between how we feel and how we act:
However in the 70s psychologist James Laird from Clark University decided to put James’s theory to the test. Volunteers were invited into the laboratory and asked to adopt certain facial expressions. To create an angry expression participants were asked to draw down their eyebrows and clench their teeth. For the happy expression they were asked to draw back the corners of the mouth. The results were remarkable. Exactly as predicted by James years before, the participants felt significantly happier when they forced their faces into smiles, and much angrier when they were clenching their teeth.
Subsequent research has shown that the same effect applies to almost all aspects of our everyday lives. By acting as if you are a certain type of person, you become that person – what I call the “As If” principle.
Take, for example, willpower. Motivated people tense their muscles as they get ready to spring into action. But can you boost your willpower by simply tensing your muscles? Studies led by Iris Hung from the National University of Singapore had volunteers visit a local cafeteria and asked them to try to avoid temptation and not buy sugary snacks. Some of the volunteers were asked to make their hand into a fist or contract their biceps, and thus behave as if they were more motivated. Amazingly, this simple exercise made people far more likely to buy healthy food.