Your mind is an instrument, a tool. It is there to be used for a specific task, and when the task is completed, you lay it down. As it is, I would say about 80 to 90 percent of most peoples thinking is not only repetitive and useless, but because of its dysfunctional and often negative nature, much of it is also harmful. Observe your mind and you will find this to be true. It causes a serious leakage of vital energy. This kind of compulsive thinking is actually an addiction. What characterizes an addiction? Quite simply this: you no longer feel that you have the choice to stop. It seems stronger than you. It also gives you a false sense of pleasure, pleasure that invariably turns into pain.

The Power of Now by Eckhart Tolle