Why do we always prepare for the worst?

Almost everyday we are faced with things that we have to do, that we would rather not do. When it comes time to do that thing (take a test specifically,) pretty much all we do is complain. I know personally I try to find excuses not to thinking it will be the most horrible day ever. However, when it comes time to do the task we go in grudgingly and come out saying that it wasn't so bad after all. Why is it that we do that? Why can't we just go in with the attitude that it will turn out all right. I think that the main reason is preparation. A good majority of the time high school students don't always prepare for a test the way that they should so they don't feel very confident. After it's all over they come out feeling like they knew more than they thought they did, and the stress is off their backs. If we can just have a better attitude on life and the things that we are facing we can make life a whole lot stressful.