This essay by the existentialist writer Albert Camus is one of the finest examples of humanist thought about the meaning of life.
In the essay Camus says that Sisyphus is able to turn the punishment of the gods into a victory by abandoning any hope that he will ever be able to reach the summit of the mountain. By accepting his fate he has become the master of his fate.
Camus intends for Sisyphus to be symbolic of human existence. We are beings faced with the knowledge that our death is inevitable and non-existence is our fate, but that if we accept this fate we can find meaning in living for the sake of living - "the struggle itself towards the heights [becomes] enough to fill a man's heart."