The pain of death

Why people fear to die? So what is the pain of death? how will it be? infact what is pain? Dictionary meaning says it is physical suffering or distress, as due to injury, illness etc.. The other day i was discussing 'death' with my friend asking him why at all people fear death when everyone knows that it is inevitable and an uninvited guest. He tried enlightening me by quoting  Mahabharata that the question i asked was one of five ambiguous questions that the world faces. The other day i saw my father dying of heart attack and what would have been his pain of death. He wanted to live and remain immortal though he is sure that he will die someday. But the day was not known and he was somehow prepared for it. The true pain of death for him is leaving his family and children with a little bit of wealth he accumulated during his life on earth. I hear heart attack is the sudden blockage of blood to heart and the heart stops pumping. So its a pinch, a pinch good enough to stop your breath. So the physical pain was not there. Yet he would have feared death for the sheer pain of leaving this world. But i am not sure. But one thing we all agreed that he had one of the smoothest exists and we are happy for that.

Again for a soldier who is fighting a battle, whats the pain of death. He is sure that death may come anytime but he is unaware about when he is going to experience death. Well, he is only motivated and encouraged by the sacrifice he does for the people he serves. The physical pain is there but he is strong enough to conquer it as his sacrifice bears that pain. He knows that he will leave his family and the nation will take care of them. So why he may fear death and what would have been his pain of death. It could be the sheer knowledge that he as a entity will no longer exist. But i am not sure. 

I have seen old age people somehow wanted to stick to their life rather than die. In this endeavor they become burdensome and hence becomes second child in their life not knowing when they are peeing and shitting sitting there. Well why they fear death and what is the pain of death for them. I am not sure.

Yet some profound people calling upon god soon after they reach 60 asking him for a smooth exit from this world and get submergence with him. The pain could be to reach God, may be. I am not sure why they fear and what is their pain of death. 

So do i fear death and his pain.. I am not sure.. if somebody asks me to die today, will i be ready to die. I dont know. i fear that dying of me will create immense sorrow to my family and friends. But the sorrow will diminish over time and memories stay with them. i fear what will happen to my mother after i die. She has not experienced the world at all in her lifetime. she has become fragile in front of my eyes after my father's death. I fear that i will leave her alone in this world and i would compel her to rue about her remaining days of life. Is it causing me the pain of death. I don't know,. may be i have to think a lot about fear of death and its pain to get convincing answers.