Hebrews 13:5: "Let your conversation be without covetousness; and be content with such things as ye have: for he hath said, I will never leave thee, nor forsake thee."
Instead of focusing on what we don't have, this verse encourages us to focus on that which we always have. The word "conversation" means lifestyle. The way we live our lives ought to be free from covetousness. Our default mode of living ought not to be a constant desire for things we do not have. We will never live happy or satisfied lives that way.