CBT is good for the times when our negative beliefs aren't supported by the available evidence.

E.g. yesterday my boss gave me some negative feedback. She also told me she thought I was an overall good worker, and that if I weren't she would have fired me already. I selectively paid more attention to the negative feedback, so my internal reaction was "Aaagh she thinks I'm a bad worker" even though she specifically said the opposite.

So it took conscious effort on my part to maintain a realistic view: "She thinks there are problems, but we talked about how I'm going to change, and I'm overall a good worker." CBT training is helpful to me in staying realistic.