The Mental Clutch
The thought processes in the mind create reactions in body, like waves on the surface of the ocean. These waves always appear in familiar formations. A certain type of waves, we call Happiness. Another set of waves, we call it Anger, and so forth. All emotions are like that--familiar patterns of bodily reactions that are triggered by mental processes.
If we are aware of our mental processes, we can, with practice, control the reactions of the body towards them. For example, a thought that usually triggers an anger reaction can be detected within the split second that it arises in the mind, and instinctively defused. You acknowledge the arisal of the thought, but you disengage its usual reaction in your body--like how the car engine is disengaged from the transmission system, through the mechanism of the clutch.
The practice of meditation helps you to develop this mental clutch. Remember how difficult it was when you first started to learn how to drive? But with practice you soon learned how to control the clutch pedal in such a subtle fashion that you were able to use it to make the car balance on a slope. Can one achieve such fine control over one's mind? Well, if you can do it with your foot, you can certainly do it with your head .
We think it is difficult because we are too lazy to try. Laziness is the greatest obstacle towards a mastery of the mind. Most of us are bestowed with reasonably capable minds, but unfortunately it is often occupied by the trivialities of everyday life. Thinking is a lot of hard work; especially when you asked to think about what you are thinking about--the mind thinking about the mind. What could be more boring than that!
But if we do not have the ability to listen to our own minds, then I'm afraid we'll always be drown in the incessant mental chatter that arises spontaneously in our heads. If we do not check this source of noise, we are nothing but noise. And already there's enough noise in this world.