Once you reach a certain place in your life and you have had to face adversity on a regular basis, you begin to expect only the negative to happen.
Up until about two years ago I was the same way. No matter how good things seemed to be going, I was always waiting and expecting the "rug to be pulled out from under my feet." Why wouldn't I expect that, it always seemed to happen to me. If I things were going well for me, someone in my family would have something horrible happen to them. Weather it was my mother getting diagnosed w/ breast cancer as I got my first job out of college or something on a smaller scale.
I always seemed to look for the negative in every situation. I was the ultimate "the glass is half empty" personality. I could get offered a million dollars from the lottery and all I would be thinking was "how long before they realize this isn't supposed to go to me." I could always find a way to turn something positive into a negative moment. All because I was used to negative things happening to me.
Then I started to realize that the only way my outlook was going to change was if I did something about it myself. I stopped feeling sorry for myself when bad things would happen and started to realize that I can't control everything. I am not the center point of the universe, in fact I am only a part of it's overall process of life. Once I realized that only I could take responsibility for my actions and that it was OK to enjoy positives in my life and interesting thing happened. More positive things started taking place in my life.
If you allow yourself to truly enjoy your high moments and stop worrying about the low moments, you will quickly realize a change in your overall mood and quality of life. You will also realize that a lot of the things that you lost sleep over due to worrying actually were not problems at all and actually worked themselves out on their own.
Enjoy you life, celebrate yourself and everything will work out!