What's so important about negative thoughts?
CBT is based on a 'model' or theory that it's not events themselves that upset us, but the meanings we give them. Our thoughts can block us seeing things that don't fit with what we believe is true. In other words, we continue to hold on to the same old thoughts and fail to learn anything new.
For example, a depressed woman may think, 'I can't face going into work today: I can't do it. Nothing will go right. I'll feel awful.' As a result of having these thoughts - and of believing them - she may ring in sick.
By behaving like this, she won't have the chance to find out that her prediction was wrong. She might have found some things she could do, and at least some things that were OK. But if she stays at home, brooding about her failure to go in, she may end up thinking: 'I've let everyone down. They will be angry with me. Why can't I do what everyone else does? I'm so weak and useless.' She will probably end up feeling worse, and have even more difficulty going in to work the next day.
Thinking, behaving and feeling like this may start a downward spiral. This vicious circle can apply to many different kinds of problems.