An aide in the prevention of depression, anxiety and psychosomatic disorders; improved breathing capacity; strengthened immune system; increased confidence and positive outlook.
Generally people like being around other happy people, thus when one is constantly sad or down there is a very real possibility that the percentage of people willing to be around are almost nil.
You can choose to be permanently grumpy or you can choose to cheer up and smile! Have you been putting off the smiles? By smiling you will be releasing endorphins in your brain which will make you feel better.