Passing on genes, in a narrow sense and a broad sense, is my best guess; your concious self is just a bewildered passenger on its brief journey from an awakening awareness to oblivion. You can, of course choose to ascribe other meaning but, assuming there's no God, it really has no foundation and melts away into nothingness upon detailed examination. There's a lot to be said for living your life in blissful ignorance rather than torturing yourself with these metaphysical speculations that lead nowhere, though, I suppose you could argue they are a pleasant diversion, if not taken too seriously.