We're actually born smiling. 3-D ultrasound technology now shows that developing babies appear to smile even in the womb. After they're born, babies continue to smile (initially mostly in their sleep) and even blind babies smile in response to the sound of the human voice.

An intriguing UC Berkeley 30-year longitudinal study examined the smiles of students in an old yearbook, and measured their well-being and success throughout their lives. By measuring the smiles in the photographs the researchers were able to predict: how fulfilling and long lasting their marriages would be, how highly they would score on standardized tests of well-being and general happiness, and how inspiring they would be to others. The widest smilers consistently ranked highest in all of the above.

Even more surprising was a 2010 Wayne State University research project that examined the baseball cards photos of Major League players in 1952. The study found that the span of a player's smile could actually predict the span of his life! Players who didn't smile in their pictures lived an average of only 72.9 years, while players with beaming smiles lived an average of 79.9 years.

Possible Preaching Angles: Joy—Although smiling doesn't always stem from genuine joy, at times there is certainly a connection between the joy on our face and the joy in our heart.