You should repeat the procedure on a daily basis until such time as you experience absolutely no emotional response whatsoever. When you can create images and thoughts of a mouse and remain detached, a witness, then you have essentially exhausted your fear. If you wish you can test whether or not the fear still remains by actually facing the object in the outside world. This is your choice. If the fear is still there, then of course you must continue with the practice until the object is no longer a disturbance in your life. The same procedure can and should be repeated with any fear that is known to you. It can be fear of the opposite sex, of heights, of darkness or any phobia in fact that you can think of.
The rationale of this technique is simple, namely that people are less likely to react emotionally to objects that are normally objects of fear, if the objects are confronted in states of relaxation. In everyday life one would jump when confronted with the frightening object, but during relaxation the emotional reaction is either lessened or nullified. In a sense the fear is overcome and the ability to face the object during a period of relaxation carries over into daily life. This technique is commonly used by psychiatrists in the following manner.
A patient acknowledges that he is afraid of something, perhaps lizards. The psychiatrist systematically relaxes the patient. Then the psychiatrist shows the patient a picture that illustrates the fear, in this example a photograph or drawing of a lizard, or describes a vivid picture of a lizard, which the patient tries to visualize. Instead of reacting with fear the patient is calmer and is shown that the lizard can be faced and that it need not always be an object of dread. From this, the patient eventually becomes able to face lizards in the outside world. The system in yoga is the same but the individual must be his own psychiatrist.
This method is an excellent tool in exhausting mental problems and their accompanying emotions, and is a good supplement for meditational techniques. The reader is recommended to use it widely to combat the more obvious, conscious fears.