I think that the fear of death is natural, normal, and impossible to overcome. The only thing you can do about it is to stop thinking about it all the time and being stressed because of it (or trick yourself into thinking that death is too distant/not that painful/positive in some way). I cope with the fear of death by just not thinking about it too much since I fail to find anything positive about future death. And when I do, I strive to use thoughts about death as a tool for making my life more productive/efficient.