You can’t control your thoughts - until you deal with beliefs of your heart. The first step to change your doorkeeper (thoughts) is to meditate on the promise of God until you feel the emotion, because that’s what makes it believable. Now that you can believe it, you can use authority and harmonize your present moment in the foundation of God’s Word and His righteousness. This is writing beliefs on your heart over and over again, until the destructive beliefs have faded away, and you are no longer tempted to think along those lines.