The only way to get rid of fear is to rationalize it and think logically. But how do you think logically about something you know nothing about? Fear of the unknown.
I'm only afraid that my inevitable immortality will be boring. Immortals rarely succumb to grief. Grief can be overcome with sufficient time. No, it is the fate of the long-lived to succumb to the crushing embrace of an all-pervading boredom that comes with having seen and done all that is to be, and can be.....
I've always had the fear of death; it's what causes my sleep anxiety, worsened by the trauma of some of my family members dying in their sleep. Personally, I don't like the idea of no longer existing. If I don't exist, I can't collect memes or eat pizza. Obviously, I can't be upset when I'm dead, but knowing that will happen, that I won't wake up again someday, does terrify me at times.