<There is but one truly serious philosophical problem and that is suicide.>
In the first page of the book, Camus offered such a question, and in other words, judging a life is worth living itself is a funtamentally philosophical problem, which also is the main topic of this book and all the points are meant to discuss about this topic. Let me talk about a Greek myth first and then I will cut into the main issue.
Sisyphus was a tragic figure in the Greek Myths, who because of the over-indulgence in pleasures of the living world was condemned by the Gods to ceaselessly rolling a rock to the top of a mountain, whence the stone would fall back of its own weight and he had to roll it up to the top again, over and over, day after day, which is a completely futile, repetitive, boring and hopeless job. Is the Sisyphus' life worth living after being condemned by the Gods? Camus had offered such an issue and let readers think about it. As a matter of fact, the Myth is only occupying one-tenth of the book. A large part of the book centered around Camus' making some references to the absurdity of life. I'm trying to sum up a few points to offer people some reference, and then I will link them to the Myth of Greek.
Camus considered the world is filled with absurdities and irrationality originating in the personally rational thinking and expectations with very noticeable contrast to the irrational functioning of the world. Therefore, the absurdity was generated due to such disharmony and disagreement--such a problem in a large part is related to the then world in which Camus was living, a world occupied by numerous wars, conflicts between ethnic groups and totalitarian regimes by then. By some unpredictable catastrophies would the irrational functioning of the world devastate people's rational expectations. Furthermore, Camus had thought that people would find the world is working meaninglessly, mechanically turning and rotating day after day--blindly without purpose. So that Camus considered that people should find their meanings on their own if the outside world is working without purpose. Facing the absurd world and destiny, we only find our own life meaning in order to overcome the meaninglessly outside world.
Futilessly rolling a rock to the top of a mountain had been likened by Camus to this world--Sisyphus was meant everybody. Wouldn't we find ourselves repeat the same thing every day? For work, after work, going to bed and getting up. The sun will rise in the east and fall in the west every day. However, an irrational and unexpected catastrophe would ruin our rational predictions. We are living in such an absurd world all the time. It's just the time when we begin to ask "why" with lucidity. Such lucidity is to the point because the kind of "the lucid beginning" would carry itself with happiness, though pains are incurred at the same time. So both pains and happiness happen while he rolls the rock to the top of a mountain, and the sadness only happens at a moment when Sisyphus, the laborer, raises his clear consciousness to be aware of the condemnation by the Gods. Sisyphus not only couldn't resist but also understands his misfortune. The only thing that could make him happy is to seek his own fate: despise destiny, be a rebel(another book by Camus, which is mainly referred by "extentialism.") He has every confidence in the eye, ignorant of the condemnation by the Gods every time he walks down to the rock. By then, he will take the helm of his own destiny, which is enough for him to be happy as a rebel. In short, the only thing he can do to change his life is to create a meaningful process. It's a fight against those sufferings inflicted by the Gods when Sisyphus rolls the rock to the top of the mountain. Such a process makes up a life worth living.
This is a mini-pocket book with a total of 133 pages. And it's not easy to read and understand, though a small volume, except for a tiny part of The Myth Of Greek that I can roughly grasp. This booklet was written in a form of philosophical prose by Camus, who always opposed being referred as "an extentialist", but those books were already marked as such kind of thoughts by later generations. His written works have been the main topic of the contemporary philosophy. It's worth reading for those peers who like doing some philosophical thinking.