The purpose of life

I and my friend often talk about it... sometimes jokingly... sometimes on a bit of a serious note...  But when I sit back and think to myself... it really appears like a question I can't find an answer to...
Going to work, hanging around with friends, movies, malls, coffee shops, ice cream parlours... is this what a life is meant to be?
Some say, its the sense of achievement in what one does...
some say, its the path OR the process of what one does...
some say, the purpose of ones' life is to give back to the society and our near and dear ones...
....
...
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Definitions and more definitions is all I have found... but nothing convincing enough.
May be I'm too small and stupid to ponder on this...  may be its too early...
but I guess it would be nice to wake up in the morning, all geared up; knowing what u're gonna do and exactly "why"...  
I guess it would be nice to breathe ones' last, with the believe that ones' life hasn't gone waste...
if only...