I always ume the worst outcome, am I nuts for being this way?

Generally speaking, I always ume the worst case scenario in situations. The reason is because if the worst actually does happen, then I won't be as shocked or upset, and I'll be better prepared to handle it. I'm scared of thinking positively, and I confuse thinking positively with getting my hopes up too high. For example, lets say I apply for a new job, then get an interview, and afterwards Company X says they'll contact me soon regarding the decision made--here is where I ume the worst; that is; never hearing back from the company, being rejected, etc. Therefore, if it happens, then I won't be as upset, and I'll move on more quickly. If I think positively all the time, I set myself up for failure and I'll be emotionally unstable. If the outcome turns upside down, being great, then I'm either confused or pleasantly surprised (this has happened to me alot lately). Am I crazy for thinking like this? What's anyone's take on this?