Great question Paul. The Human Race feels 'ya.
I think GTD makes tracking things easy. Perhaps we could also use it to set an action, say meditation, that would help us minimize negative self-talk and put ourselves into a more relaxed, positive state. Nice.
Getting to the heart of the matter, I think, is beyond the scope of GTD. In my experience, I have generally found that we all have a deeply held set of beliefs and perspectives about ourselves, others, and the world we live in that drive our every thought and action.
Shine sweet freedom: The belief we have may not be the truth - it may just be a version of the truth among many other possibilities.
What if every negative thing we believe about ourselves is wrong?