My fourth tattoo, I got it because of the starfish story:
A man was walking along a beach after a storm. The beach was covered with starfish because of high tide, and he was throwing them back into the water so they wouldn't die. Another man asked why, saying "You'll never make a difference, next high tide it'll be the same."
The first man picked up another starfish, threw it in and said, "I just made a difference to that one."