How does smiling often make a person's life better?

Many ways: Need to get the psychologists/psychiatrists in on this. Smiling projects a positive and friendly attitude. This becomes contagious. Before you know it, you have everyone feeling better. Positive reinforcement this is. How many times do you see a baby smiling and find yourself smiling back, and maybe talking baby talk. You just feel better. I do believe there is also a chemical change which occurs.