Why do we live

Few days ago I read a book "Nirvana" from that though I didn't got Nirvana, I was wondering why we live, what is the ultimate goal of our life, are we born just to grow old, have sex, marry, have kids and serve them for next 20 yrs of thr life as our parents did for us become older and older and die one day , are we born just to do this ,or is there some driving force for our life that governs us to do our work, I don't think any one can find the answer of these questions, but still everyone lives and lives and is living for past, I don't know how many centuries. Why is this universe existed after all, what if thr would be no one, no living beings no water nothing, who the hell governs all these things , I just want to find answers of these questions before I die