The thought that some day I will cease to exist used to terrify me. It still does, but it has lost some of its sharpness since I decided to work against my fear of dying.
The fear of death was seriously bothering me and I thought: " You can either try to achieve immortality or try to loose your fear of death within your lifetime."
The second one is a solvable problem, the first one, for me personally, not. It gives a strange comfort that one day I might be free of the fear of death even if I know that still I will die.