People who smile -the warm kind of smile that includes the eyes- "have less anxiety, fear sadness, pain and despair in their lives... They reported feeling more connected to those around them. The smile helps trigger greater trust and intimacy." according to Dacher Keltner in his recent book Born to Be Good. This is so true in the classroom. My first hour never smiles and it is such an effort to get through the class period. The rest of my classes do smile and they are a joy to teach. I try to smile even when I don't feel like it and it makes a difference in the attitude of the room.