This exercise is very helpful in everyday life when your mind is trying to take you back down well trodden tracks:
As soon as you catch an unwanted thought, visualise a big STOP sign. Stop your thought in its tracks with the stop sign and prevent the negative thought cycle from picking up speed. Pause for a moment and consciously select your new, positive thought.
A good idea is reminding yourself over and over again that thoughts are beliefs. They are created by us, which means that we can also change them. Pay attention to your thoughts and beliefs to become aware of your limiting beliefs. Mindfulness is very helpful in becoming aware of your unconscious thoughts. By being mindful of your usual, no longer wanted thought patterns and by keeping an active focus on new thoughts and your new goal, you will be able to step away from your old habits and create new ones.