Fear isn't really the correct word, but knowing that everything will end and that everything that has ever been done will be meaningless when it's all over gives or gave me a horrible feeling from time to time. It's like nothing you do will have any meaning in the end, and not even half a century after you die you will be forgotten - if you did something outstanding, it will just take a little bit longer. That can of course be advanced to the concept of general vacuity of existance.
I've always been kind of a philosophical guy and things that really bothered other people didn't bother me. It was more of a general depression that was stronger or weaker from time to time.
I was raised in a Christian family. Not very religious, but with the belief of a generous, saving god. That concept seemed so constructed and irrational on many levels to me and so obviously born in the deep blind desire of having a meaning in life that I just couldn't
believe.
After a longer process of thinking I came to the conclusion that there is indeed no meaning that is ultimately given to you. If you need a sense, you have to create it by yourself. That being said, I try to live with strong principles and have adopted a utilitarian lifestyle - a concept that convinced me most because it tries to build an ethical approach upon logical reasoning with the premise that suffering is negative and should be avoided and happiness is positive and achieve worthy and I feel better than ever before.
Realising that time is just another dimension like room was a small factor, too, because in the end, something that happened 10.000 years ago is as equally important as something that happens now or tomorrow, at least that's what I think.
Okay, I went a bit off with that.