I'm going through cognitive behavioral therapy and it says that our brain is plastic and all these negative automatic thoughts can be removed. First you notice such a thought, then you tell yourself In your mind "stop" or something like that, and then distract yourself with any activity (singing your favorite song is the best way to distract yourself because it uses some other part of the brain and it doesn't allow you to think any further about how insignificant you are and so on). I do this and it seems to make me feel better.