Meaning of this life

Yesterday on my return journey, i was reading an article from Paulo Cohelo's recent book "like the flowing river". The article is about living a life. Reading it, took me back to one of the issue i have been grappling with since a long time, more so, in the last few years. The issue is "Why do we live ?"
If we look around, we see number of creatures who are just concerned to pass their day. An ant doesn't need to worry what legacy she has to leave. Its function is just looking for the food and to store it for consuming it later on. All other animals do similar things. But as human, sometimes we think that whether we are destined to the same fate which is assigned to these animals or do we have some superior function. Are we supposed to find hidden meaning and purpose of the life and strive to achieve it ? I don't know what Gautam Buddha, Mahavir Jain or Vivekananda wanted to achieve. In whose discovery they set themselves for. Atleast knowing it, will pave the way for search.
But till knowing what are we supposed to do other than things we do to satisfy our abject needs, this life bears complete similarity with the life of all other animals. Till then, we live to die.