With happiness you can give another person life! There are people who suffer terrible pain but cannot express what is in their heart. They would like to speak about their suffering but they have nobody to whom they can explain what is really in their heart. This leaves them full of pain and anguish. When you come to such a person with a smiling face, you can literally give that person life. To give a person life is not an empty gesture. It is something very great.
(Rebbe Nachman of Breslov)