Catastrophizing is the mental and emotional process of thinking that the probable results of an event (or possible event) are much, much worse than is likely. You worry incessantly about a situation and foresee only the worst possible outcomes.
Basically a type of anxiety, catastrophizing can keep you from taking the healthy risks you need take in order to keep growing as a person and in your career. If you always assume (and believe in) the worst outcome, you’ll seldom be able to create the best outcomes. To learn more about why you may be catastrophizing and how to develop a mental frame that lets you change that response, start with this article on overcoming negative thinking.