The mind is a very powerful tool. You can only use it so much. A good way to use the mind to your advantage is to remember how to use it to its maximum power. This goes for the mind and the emotions you experience. If you are over-thinking something, you are not being aware of it, you are just focusing on it, which is like over-thinking a small child. You are not truly present with what is happening in your life.
The mind is essentially a device for finding the solution to problems. You can find it within your mind and use it to resolve problems, solve problems, or to fix other problems simply by using the mind.