Think in positives.

We should think in positives.  I say to people, "Give me the opposite of the negative thought you're thinking," and they can't do it.  The difficulty is a habit. But you can change a negative habit into a positive habit. Just put in a positive thought with more power than the habitual thought. It'll overwhelm and knock out the negative thought. One powerful thought can knock out hundreds of negative subconscious thoughts at once. 
What makes the difference in the power of a thought?  The amount of resolve, determination, or willpower that you put behind the thought.