According to Albert Camus's ideas on absurdism, it is completely unnecessary to answer this question because the more you attempt to understand what happiness is, the less happy you will be.
I really liked the previous response to the question but i just thought i'd add the Albert Camus's reflection on "the meaning" of life. He was a huge "absurdist" meaning that he strongly believe that our entire purpose in life is set on making sense of a world filled with nonsense. It's like trying to put together a puzzle with all the wrong pieces. So i believe that with this in mind, "absurd" is not necessarily impossible, but impossible to us at the moment. Absolutely nothing in this world is impossible, because nothing fits together logically in the first place. Some questions are to remain unanswered- like some pieces will never fit in a "chaotic" universe like ours. I mean, think about it! Who could imagine a world where you are surrounded by decisions that branch your present timeline into another and another and another, creating an inexplicably infinite multi-verse of just your universe. Imagine all the other dimensions of every other being on this earth, solar system, on this galaxy! Anything that can happen, has happened in some plane of time. It's just a chaotic world of never ending possibilities.
That idea, personally, just brings the "live life to the fullest" saying into a whole different perspective, but i'd love to hear another view on the matter. : D
