Negative thoughts are very common. There is research that says that our brains look for negativity for survival. Back when we were in the food chain, we had to pay attention to things to avoid becoming some predator's meal. Now, we have less concern about this kind of thing, but our brains are still the same. Negative stress and anxiety often comes in the form of negative "what if" questions that can plague us. We can use the feelings these thoughts produce as a trigger to remind us that we are thinking negatively and also trigger us to take positive action. Positive action may not fully cure this right away, but it will definitely help you start heading in a better, more positive direction.