There is a seeming paradox in one's purpose for life. If your purpose is to find happiness for yourself, then that is primarily a self-serving goal. There is nothing wrong with being happy and everyone deserves to be happy. Where does the paradox lie? It is impossible to find happiness by pursuing happiness as outside oneself. It is only when you let go of the pursuit that happiness comes. This is because happiness outside yourself is attached to other things that are transient. You have to dig deeper than self to get to your true Self. You know you are truly centered when your focus is not on the end result of happiness but on helping others find happiness.
You discover that being happy is part of your True Nature. You do not have to do anything to be happy; you are Happiness. Serving others and helping them along on their path is a natural extension of the Joy that arises from within. What gives us meaning and purpose in our lives is the journey towards God, the source of all happiness, simultaneously realizing that there is no where to go as we are already there. God is here in this present moment. The mistake is to think that there is a destination to get to. There isn't. The secret is to be with this Truth. This Truth is that God is present as we strive towards her; God is in the journey, not in the destination.
So, back to your purpose for life. In truth, there is no paradox as long as we speak of things in the correct context. A life built for pursuing Happiness that feeds your soul is one and the same as a life that seeks after God. There is only one Good in the Universe and that is God. God alone can provide the only nourishment for your Soul. A mistake is seeking after happiness attached to temporal objects in this world. In this plane of existence, such happiness is short-lived as you will eventually encounter its opposite, the associated sadness when that object disappears or changes. Do what you wish to be happy, without attachment and without expectation of any result. Follow your soul-inspired dreams and be filled with the everlasting Happiness from God.