A smile is an incredibly powerful tool of communication. If we arrive in a foreign land, or are in a group of strangers, a sincere smile from another person helps us feel at ease immediately, almost as if we were with old friends instead of in a sea of unfamiliar faces.
For a smile is familiar; it gives us the message of acceptance, love and understanding, appreciation and safety. As a result, when we receive a truly warm and loving smile, we relax and let down our defenses. It activates our parasympathetic nervous system's "relaxation response", producing distinct physiological changes in our endocrine glands, our nervous system, our muscular and circulatory systems, our respiration and our digestive tract; in fact, nearly every system in the body can be dramatically affected by the simple fact of receiving a smile.
Just as a smile is effective in communicating with other people, it is also an amazingly powerful tool in communicating with ourselves. For we are always communicating with ourselves, consciously or subconsciously, but unfortunately the message is not always positive. Self-loathing and low self-esteem are all too common in modern society, and aside from the psychological and sociological effects of a negative self-image, our own health may suffer as a result. Many serious illnesses such as cancer, heart disease and diabetes, are often preceded by long periods of chronic negative emotions.
A smile is a curve that straightens a lot of things!