Happiness is what you make and you can't let anybody tell you what it is. Happiness can be what ever picture you want to paint. Happiness could also be dodging the shots lifer has to throw at you, but your always keeping a smile on anyway :)
There have been several studies on this topic in the last few years. The result: happiness happens when all the primary relationships in a person's life are in good shape. It's not the fall-in-love euphoria, or the carnival excitement kind of happiness. It is contentment with comfortable and reciprocal social relationships. Examples: siblings, parents, extended family, friends, teachers, etc.
Well, if you are a Christian (Catholic, specifically), then you would know that God put us here to love and serve Him. That is the meaning of life. That has always been clear to those of us who have studied Christianity. Many people, once including me, wonder what God does to deserve our love and praise, why only He should be loved above all things. Well, first of all, He is the Supreme Being, holding everything in existence. If He ceases to do so, we will all vanish, but He will continue to exist. Second, He created us, without Him we wouldn't be here. Third, He came to Earth in the form of a human 2000 years ago (Jesus Christ), to DIE for us. He came here, was crucified, beaten and spat on by His own creation so that we wouldn't be damned to Hell. He died for our sins. He was raised to life once again and ascended back into Heaven. Fourth - God will give us everything we ever wanted in return for our love and praise. He will give us a mansion, riches, thousands of friends, and Eternal Life in Heaven forever. The Meaning of Life is to love, serve, and praise God forever. That is the secret of happiness. In heaven, we will have eternal happiness and joy forever.