Meursault is forced to live in a cell without any pleasures, such as his cigarettes or the "love" of a woman. When this happens, Meursault recalls what his mother told him. She said that one could get used to just about anything. When Meursault realizes and understands that this is just part of his punishment, he becomes indifferent, as he always does, and accepts his situation. Though Meursault had mentally accepted his situation, his body still suffers withdraw symptoms and sexual urges. Eventually however, his body "got used to it" as well. He passively defies punishment by accepting his situation and enjoying himself in jail. That is when Meursault's punishment isn't a punishment anymore. When Meursault is condemned to death, he does not act surprised, although he wishes he did not have to die. After a while he accepts that too. It did not matter to him that he is going to die, since he reasoned that he would have to face the same dilemma in a few years anyway.
Sisyphus on the other hand, is damned for eternity to perform a futile task, which is to roll a rock up a hill where it will fall back down, and the process repeats itself. If he were to view his fate decreed upon him as punishment, for the rest of forever, then he would only make his presently bad situation into an eternity of horrible torture, which was the original design of the