People who are prone to anger usually have a low frustration tolerance and a tendency to interpret events through a persecutory lens, meaning they tend to feel easily victimized and to take what are often random and indiscriminate acts as a personal affront.
When something upsetting triggers your primitive wiring, it sounds your body's alarm bells: You experience shallow breath, a racing heart rate and tense muscles.
In order to cultivate a more calm and composed disposition, you need to counteract these symptoms. To do this, there are a number of techniques I suggest you practice:
The next time some moron cuts you off in traffic, instead of chasing him down to hurl epithets his way, try to take a deep breath, which means breathing from your lower belly, or your gut, instead of from your chest. When we breathe from our chest, our breathing is shallower and tends to excite the nervous system, whereas a deep breath tends to calm that system down. Repeat a calming word or phrase, such as "relax," or "it's going to be okay." Remind yourself that you're in control of your responses, and that no one--much less some chump in a beat up Corvette--is worth the sacrifice of your peace of mind.
Practicing yoga, engaging in cognitive behavioral therapy, guided visualization and/or meditation are all very effective at relieving stress, decreasing anger, and increasing mental clarity, performance and wellbeing.
Put a premium on your sleep, as studies show that lack of sleep tends to increase irritability and makes people more prone to frustration and depression.
Anger has become quite a problem in our culture, where daily frustrations and stresses sit against a backdrop of high performance expectations and a desire for immediate gratification. So, the good news is that anger management workbooks, courses and therapies abound. Below you'll find a list of those that you may find helpful.
Useful Resources for Anger Problems:
The Anger Workbook for Women. Laura J. Petracek, Ph.D.
The Anger Trap: Free Yourself from Frustrations that Sabotage Your Life. Les Carter, Ph.D.
Letting Go of Anger: The 11 Most Common Anger Styles and What to Do About Them. Ronald t. Potter-Efron, Ph.D. Patricia S. Potter-Efron, M.S.
The Anger Busting Workbook. James Baker.
What you want to do about this depends on what outcome you seek. If you want to "manage" these angry feelings, then learn to count to 10, do deep breathing, or distract yourself.
If you want to "master" angry feelings, then you need to change the basis for anger, as well as release the built-up angry energy you already have. You will want to do this in a way that is not hurtful to yourself or others.
We get angry because our idea of "how things are supposed to be" gets violated. To use the freeway driving example, if we think "other drivers are not supposed to weave in and out of traffic and cut me off," whenever that occurs, we will get angry. In your case, since the anger has been held in so long already, you are likely to become furious or raging.
Anger is signaling you to change your own ideas. They are incorrect. Is it really true, for example, that "other drivers are not supposed to weave in and out of traffic and cut me off"? No! They do it all the time. Instead, remind yourself that "__% of all freeway drivers will weave in and out of traffic and cut me off. This driver is part of that __%." Keep doing this, and you'll find yourself no longer angry over this issue.
It would be helpful for you to understand how anger works and what you can do to get in charge of it (which is totally possible--I am a Recovered Angry Person, and I've helped lots of people attain this "title," too). Resources that might help include: Harriet Lerner's book, The Dance of Anger, my CD "Stop Anger Now" (a one-hour minicourse), my downloadable booklet "Bouncing Back from Anger and Argument."
Because you have been holding onto anger long enough for it to build to such explosive proportions, I would suggest you release the old angers with the help of a psychotherapist. The basic principle is to "get anger out of you, but not onto others." You can do this by scribbling with crayons on a large (newspaper size) piece of paper while allowing yourself to make angry sounds as you think about the things that anger you, by shouting into some trees deep in the woods, by shouting your angry feelings into the wind at the beach, or by sitting quietly ad repeating aloud "I'm angry, I'm angry, I'm angry...." in a cadence, then allowing yourself to say aloud what comes up that you're feeling angry about, then returning to the cadence. It can be scary when you have so much anger, to be alone in releasing it, which is why I recommend working with somebody knowledgeable as you do this.
Also, once you "open the door" you won't be able to close it. This will be good, in the long run, but can scare you. It took me two years for all of my anger to be released! It angered me that it was taking so long!!
This is another reason why having a guide (a psychotherapist) is so important.
There is lots more on this topic. Because I had so many held-onto feelings as a younger person, I made it my business to find out how to work with emotions so I could become MASTER of the emotions, instead of letting them run my life, and have thus become known as "The Emotional Pro." I'm happy to answer more questions.
It's great that anger is presenting itself so powerfully in your life that you feel the need to do something about it. That means you're on the verge of getting free of its tyranny!