How many times do you catch yourself saying things like, "I don't do well in social situations," "I don't like going to the city." "I don't like animals." This type of thinking is called overgeneralized thinking; which means, you store one single negative event in your memory, and then use it to make wide, across-the-board generalizations. It's not ALWAYS bad to think in this way IF you have gathered sufficient evidence to make such a claim. Sometimes, thinking negatively going into a situation can cause the situation to go sour because of a sour attitude. Overgeneralizing is a way for your brain to skip over thinking deeply about what caused frustration, anxiety, fear, or disappointment in a situation. Your brain will create an untrue belief based on a sweeping statement. This type of thinking is MORE likely to cause more frustration, anxiety, fear, and/or disappointment because it is making a negative generalization about your self that usually infects your thinking to make you believe it can span other situations too.
Take control of your thinking by recognizing when you are overgeneralizing and you may realize that your days might start going better because you are giving yourself the benefit of the doubt in situations you have already encountered that may just not have gone well once.