Aesop
A fox was hungry one day, and he happened to find a vine with some delicious-looking grapes hanging from it. He tried to reach the grapes but found that the vine was too high for him.
He tried and tried, but he just couldn't reach them. Finally, he gave up and said, "Those grapes are probably sour anyway. I don't want them."
But the grapes were not sour. They were sweet and juicy, and the fox had missed out on a delicious treat because he had not been willing to try hard enough.
Moral of the story: Don't give up easily. If you want something, keep trying and you may eventually achieve your goal.