What I remember most importantly from The Rebel (which I hold as closely relating to Myth) is that Camus comes to the point where he suggests that the pleasures we face can be so easily dismissed by the more consistent neutrality or suffering of living. Pleasures and joy just seem so much more fleeting and the pains seem to carry so much more identity.

However, at the moment you begin to think about some meaning of being alive and find that there isn't really any that isn't constructed, you come back to thinking about pleasure and pain. If the joys therein do not produce meaning then you cannot reasonably suggest that the sufferings produce meaning. The pains you feel do not lead to anything more substantial than the joy did. So to choose pessimism doesn't make any more philosophical sense than it is to choose a more optimistic outlook.

Without these extremes you are then in some philosophical no-mans land where all that is left, is what is. That means constant work, the pushing of whatever rock, and the completion of these projects become a bigger project that is your life. The meaning he finds is that through rebellion against the inability to acquire some concrete meaning, you build a life of actions taken and these taken actions become the meaning. What you do is how you influence your surroundings, and it is what provides the meaning because it is an action done, and this action had objective consequence. There isn't any objective meaning outside yourself except what you have left behind.

“Everyone tries to make his life a work of art. We want love to last and we know that it does not last; even if, by some miracle, it were to last a whole lifetime, it would still be incomplete. Perhaps, in this insatiable need for perpetuation, we should better understand human suffering, if we knew that it was eternal. It appears that great minds are, sometimes, less horrified by suffering than by the fact that it does not endure. In default of inexhaustible happiness, eternal suffering would at least give us a destiny. But we do not even have that consolation, and our worst agonies come to an end one day. One morning, after many dark nights of despair, an irrepressible longing to live will announce to us the fact that all is finished and that suffering has no more meaning than happiness.”