Smile :)
"A smile costs nothing, yet creates much.
It enriches those who receive it, without impoverishig those who give.
It happens in a flash and the memory of it can last forever.
No one is so wealthy he can get along without it.
And no one is so poor that he is not enriched by its benefits.
It creates happiness in the home, fosters good will in business,
and is the countersign of friends.
It is rest to the weary, daylight to the discouraged,
sunshine to the sad and nature's best antidote for trouble"
Author Unkown