Thoughts that recur seemingly spontaneously in your mind can be examples of intrusive thoughts, sometimes called obsessional thinking. Obsessive thoughts are driven by anxiety. It's easy to say to oneself, 'don't worry about this' or 'stop thinking about it'. But accomplishing that may be another case entirely. For those coping with obsessional thoughts, not 'worrying' or thinking excessively about the issue can feel impossible. If you are unable to cease dwelling on bothersome thoughts, or stop thoughts that cue impulsive behavior, you may be dealing with obsessional thinking or 'unwanted thoughts.'
For some, breaking the power of recurring thoughts is as difficult as sleeping when one has insomnia. Substituting a healthy thought in place of an unhealthy thought can have some effect. As with most disorders that are not clearly understood, hypnosis can be an excellent method of regaining control of runaway thoughts.