That old chestnut?
Girls is walking on a beach. Sees dozens of Starfish washed up on the shore. She starts throwing them back into the ocean. A man walks by and says, "Why do you keep throwing those Starfish back into the Ocean, there are so many, you can't possibly save them all..it really doesn't matter." She picks up another Starfish..throws it back into the Ocean and says, "It mattered to that one".