Once upon a time, there was a king who ruled a prosperous country. One day, he went for a trip to some distant areas of his country. When he was back to his palace, he complained that his feet were very painful, because it was the first time that he went for such a long trip, and the road that he went through was very rough and stony. He then ordered his people to cover every road of the entire country with leather. Definitely, this would need thousands of cows' skin, and would cost a huge amount of money.
Then one of his wise servant dared himself to tell the king, "Why do you have to spend that unnecessary amount of money ? Why don't you just cut a little piece of leather to cover your feet ?"
The king was surprised, but he later agreed to his suggestion, to make a "shoe" for himself.
Moral of this story :
To make this world a happy place to live, you better change yourself - your heart; and not the world.