Perceive grace and you will naturally feel grateful. Grace is unearned. It is a free gift. If you believe in grace, you believe there is a pattern of beneficence in the world that exists quite independently of your own striving and even your own existence. Gratitude thus depends upon receiving what we do not expect to receive or have not earned, or receiving more than we deserve or earned.

Robert A. Emmons, Thanks! How the New Science of Gratitude Can Make You Happier