How does one begin the process of conquering thoughts that should not be? Try this very simple exercise and if you desire share what you experienced. Think a thought; then vocalize the alphabet; numbers; the names of your children; your parents or whatever just so long as you don’t vocalize what you are thinking. I’m not going to share with you what you experienced; I’m eager to know what you experienced and I will respond to you.
Also when you saturate your mind with the Word of GOD and begin to speak and live according to the will of GOD; you will find that your thought patterns will have changed. I’m not saying that you will not at anytime have a thought that you should not have. Most definitely temptation will threaten your thoughts.
Those who are dominated by the sinful nature think about sinful things, but those who are controlled by the Holy Spirit think about things that please the Spirit. So letting your sinful nature control your mind leads to death. But letting the Spirit control your mind leads to life and peace. Romans 8:5-6