Consider a simple example where the brain gets confused to know the temperature of the water. Fill three different bowls namely A, B and C with water of different temperatures. Let bowl A is of 50 degree centigrade, bowls B is of 25 degree centigrade and bowl C is having water of 5 degree centigrade. Now dip your left hand in bowl A and the right hand in bowls C. After about 2 minutes put your both the hands in bowl B. Now the same water of bowls B will give a cold feeling to the left hand and a warm feeling to the right hand. After some critical time interval the feeling of two different temperatures will cease as the blue prints of the previous conditions of both the hands get replaced by the common condition of bowl B.

The purpose of above example is to explain that if any condition or process of the body is allowed to continue beyond certain critical time, the brain will cease to recognize it as an changed condition and will adopt it as a part of normal body process. On the same principle the body inherits chronic diseases where the brain looses its power to recognize it as abnormal condition. Thus, there can not be a permanent cure of any disease till the brain is not having a blue print of its healthy condition or a blue print of little fainted symptoms of the existing disease. The brain need to have a picture in its memory that it can use to change the present status of the body condition.

Thus, a simple exercise can be very effective to cure some serious diseases. The patient should keep visualizing its healthy condition. For this purpose, patient should spend most of its time watching his own photos or videos of the happier days. The patient should also avoid watching destructive events and should spend maximum time to hear his favourable music. 

We know that viewing of any event has immediate effect on our body. Some individual starts weeping in the company of weeping persons without even knowing the main cause of their agony. Don't you think that on the same principle one can acquire a disease on just watching a diseased person? Yes, there is a chance if the person gets too sympathetic towards the sick person and starts visualizing his own image in the sick person.

So, a positive thinking will certainly have a good effect.