I read a story from the book "Way To Be" by Gordon B. Hinckley that I really liked. It illustrates how being kind not only benefits the person you are helping, but, it also helps you.
"An older boy and his young companion were walking along a road that led through a field. They saw an old coat and a badly worn pair of men's shoes by the roadside, and in the distance they saw the owner working in the field.
The younger boy suggested that they hide the shoes, conceal themselves, and watch the perplexity on the owner's face when he returned.
The older boy thought that would not be so good. He said the owner must be a very poor man. So, after talking the matter over, at his suggestion, they decided to try another experiment. Instead of hiding the shoes, they would put a silver dollar (which was then a commonly used coin) in each shoe and see what the owner did when he discovered the money.
Pretty soon the man returned from the field, put on his coat, slipped one foot into a shoe, felt something hard, took his foot out and found the silver dollar. Wonder and surprise shone upon his face. He looked at the dollar again and again, turned around and could see nobody, then proceeded to put on the other shoe. When to his great surprise he found another dollar, his feelings overcame him. He knelt down and offered aloud a prayer of thanksgiving, in which he spoke of his wife being sick and helpless and his children without bread. He fervently thanked the Lord for this bounty from unknown hands and evoked the blessing of heaven upon those who gave him this needed help.
The boys remained hidden until he had gone. They had been touched by his prayer and by his sincere expression of gratitude. As they left to walk down the road, one said to the other, "Don't you have a good feeling?" adapted from Bryant S. Hinckley, Not by Bread Alone, Bookcraft, 1955, p. 95"