My purpose of survival

Suddenly I am dumbstruck by the thought why am I living. What makes me feel I should continue to live. What is that I gain by extending my life to next day next hour next minute next moment. This question doesn't arise when I am surrounded by people. But when I am alone I keep thinking....there is some force either within or outside me that keeps me going and keep thinking why it is going and it goes and thinks and goes and thinks and on and on and on
What is the moto of my survival....our survival in this world in this 20th and 21st century. Definitely world doesn't need everyone of us to sustain the mankind. It is already overflowing. Then what In nature has kept me moving. It is definitely not god's wish (though I am not yet ready to accept it if at all it exists). Then what is that ticking my clock and making me move.
My life on earth is hardly going to change earth's history. Ofcourse I have all the potential to create history. Not only Me everyone has potential to create history. But earth remembers only few men. Few glorious men. Rest are either forgotten or have become unnoticed or least we have only used their remains to fuel or automobile.
Man's life span of 100yrs caters to 10^-17 of the earth's history. We are so intimidated by earth that it respects cockroach's history more than the more sophisticated Homo Saipan.
Still our haughtiness hasn't reduced. We dominate nature trying to prove our superiority only to be fooled by the nature. When does this haughtiness conquer a man. The moment he feels he knows something. The more he thinks he has acquired knowledge the more trifle he becomes. The more and more I read the more I tend to be humbled by the vastness of the world and things beyond this world unfathomable by me.
I can't think of a life that I would have 20years from now. What is that I am going to do.....I have a degree a job .... Will get married will beget children will raise them and then then then what..... My lifetime gets over. In the mean time I might think of charity ....brotherhood.... World peace etc etc then what satisfaction to my life...... Then after that what will I get what will I become may be a good husband a good father a good friend a good helper a philanthropist then I will go into those history books......then my body will be buried in the ground and may be used as fuel millions of years later......what will happen to Chandramouli as a soul......what will it do where will it go and  seek what
All these are my unanswered or I should put it that I have not tried to find out an answer to these .....will they come from within or should I search for it......my experiment has begun or is yet to begin I am not sure. But rest assured I am not going to stop until I find that force which keeps all us going....help me find it