Negative self talk can have a very bad effect on your career as it can cause you to become a much less confident worker.
Self talk is very important for how we feel about ourselves. We often come to believe the things that we say to ourselves in self talk. If we see negative things, we will end up thinking that we are not competent or dynamic. We will see ourselves in a very negative way. If we see ourselves in a negative way, we will tend to live up to those attitudes about ourselves. Our work will suffer and our careers will be stunted.