What to do with bad thoughts.What you dwell on is a matter of choice.  Thoughts can only become a realty when attention is given.Casting down imaginations,weighing them against principles of righteousness.

2 Corinthians 5-6

 ⁵Casting down imaginations, and every high thing that exalteth itself against the knowledge of God, and bringing into captivity every thought to the obedience of Christ;

 ⁶And having in a readiness to revenge all disobedience, when your obedience is fulfilled.