A theory on life
What is the purpose of life? To live. Yes, it is simple. To live needs to be taken two fold though as aforementioned: literally and metaphorically. Literally, to live is to survive – during one's own life and, possibly, “eternally” through the procurement of children. This is built into us at an animalistic level.
The second half to living is a metaphorical aspect. As an ephemeral entity, this is prone to change and relativeness to society. In America, it is written in black ink what our purpose is – the pursuit of happiness. We seek happiness in everything we do, and in the end we find it is the journey that is important and not always the destination. I cannot say what would make everyone happy, but I know some things can lead to happiness – working with one's own hands, enjoying even the little things of everyday life (don't forget to look at the world around you with new eyes, as if you haven't seen it before), letting yourself go and just dance, having a pet (one that you can play with), finding someone to love and spend your days with…
In the end, I believe the purpose of life is simply to live. The first step is simple, all we have to do is breathe. The second is a mind trick that we usually only learn in old age when we look back at our journey and realize how truly happy and ignorant we were of it.