What's the purpose of life?

I had been thinking about this question for a few years. What is the purpose of my own existance? As Sigmund Freud (1856-1939) mentioned in his book, Civilization and its Discontents, "it has not yet received a satisfactory answer and perhaps does not admit of one". As a practical man, I still have to give an answer, and the best answer I come up till now is "making people around me feel happy, because that makes me feel happy".

As I practise this more and more, deeper and deeper, I have almost lost my own goal, my own aggresion. This is because fulfilling the needs of others might sometimes restrict my own desire. Desire is the drive of everything; even "fulfilling the needs of others", in itself, is a desire. What I am confronting is an imbalance of different desires within myself, some being my own wish, some being wishes of others, and these wishes cannot co-exist.