Picture a thermometer that measures the amount of anger you are feeling at any given moment. Imagine that when you are slightly irritated or frustrated, the mercury begins to rise out of the bulb of the thermometer. When you begin to feel the anger building but are still able to control it, the mercury rises about halfway up the thermometer. When you get really upset and your anger is boiling, imagine the mercury rising to the top of the thermometer. Rate your anger on that thermometer from 0 to 100 where zero means you are completely calm, and 100 means you are in a complete rage.
Use your anger thermometer to practice making anger ratings. A good way to get started is to think back on recent past situations in which you were angry, and then use the anger thermometer to rate just how angry you were during each situation.
The goal in rating your anger is to recognize that anger operates on a continuum; that it moves smoothly up and down between calmness on the one hand and rage on the other. People with anger problems sometimes don't get the continuum nature of anger because they experience their own anger as an either/or sort of thing; things seem to be either "fine" or "furious". Even though anger appears to be an 'on' or 'off' sort of thing for these people, this is generally because they are only counting the times when they are the most angry as episodes of anger; everything else is lumped into the 'fine' category. With sufficient practice, even these people can learn to distinguish ever finer shades of anger and calmness.
Anger ratings are important because they provide feedback about how likely you are to lose control or explode at any given moment. By training yourself to recognize when you are getting increasingly angry but are not yet out of control, you improve your chances of being able to maintain control by taking steps to reverse the upward trend of your anger.