The piece reminds me of a very basic principle for parents and teachers, namely, when there is an unwanted behavior, stop the unwanted behavior and replace it with what is wanted. Often that means ignoring/not reinforcing the unwanted behavior, and reinforcing the desired behavior. The writer is saying to do the same thing with unwanted thoughts, which makes sense. The problem, of course, is that it is sometimes easier said than done. Someone said thinking makes a fine servant and a terrible master. That is very true. An effective method of keeping thinking a servant, of having my thoughts rather than my thoughts having me, of conquering unwanted thoughts is basically practice of meditation or mindfulness in which I learn to be aware of but not hold onto my thoughts, particularly unwanted thoughts, and let them pass through and pay attention to wanted thoughts if I so choose. This has had some value for me, and any day now I'll get real good at it. I need patience to practice and get better at the practice. My story is of a failure last night, when I woke up in the middle of the night thinking about a troublesome matter and I tried to let it go but it hung on and I hung onto it and I lost a lot of sleep. Maybe I'll do better next time.