It is happiness that pushes us to live and sadness that drives us to live.
I guess it was when I was sad that I struggled myself to live a life , made a point clear in the inner self inside of the deep inside that I shall Die while I am alive,
Sadness isnt so very bad as it seems to be when it passes your space , but once it has passes it gives you a reason to smile ... be happy and laugh on the unhappy moments and feel proud of the successes you gained after the bouts of unhappiness.
Sadness comes from varied reasons, those which are due to the uncontrolled mistakes or lazy mistakes you commit are the ones which hurts and leave behind there footprints for us to mark them so that the life's map doesnt follow that route again and even if it does it is with carefull eyeing on the pothholes in the road.