Purpose of Life ?

This blog was triggered by an story I came across yesterday :

A lady driving on a highway, gets distracted for a brief moment and hits the gravel on the side and her car overturns and catches fire. She is stuck inside . Another car with a elderly couple was driving behind her . The man stops runs to help this lady , while the wife dials 911. The man manages to pull the lady out of her burning car. Lady is safe but right then the man has a heart attack and dies.

I like to consider I am fairly practical person and find the concept of destiny, spirituality, sometimes even God a little hard to digest. Maybe I would have just dismissed the death of the guy , as a mere stress induced response he had during the whole event. There is a sense of comfort in that statement for me . But if I want to look at it from a whole other perspective, its pretty darn disturbing for me ...even scary . Are we all here with predestined scripts written or just random events happen based on our decisions ? How does one explain this complex dynamics of one person's life (and death), affecting another person ? What would have happened to the lady if the couple had waited another 10 mins at the rest area ?

I have read enough of thoughts and writings on such topics , but not one of them has convinced me till date , about my purpose in life....the big picture remains blurred even today.