Anger management folks will tell you that an outside force can't make you angry; you must decide to become angry in response to the force.
I'm sure they will. In some cases that may even bear some truth. However, there are cases where you (not you specifically) become angry and do not necessarily want to, or understand why. That's where "programming" as I was talking about earlier comes in. Here's a quick example before I head out to work: I worked with a lady one time who would ask me to do things once in a while. Nothing out of the ordinary really. All things I used to do with absolutely no problem for the person I worked with before her. Yet somehow when SHE would ask me to do those things it would literally trigger a response of anger and resentment within me. I couldn't control it. I had no idea why it was happening.
So I started "soul searching" or whatever you want to call it. Trying to find out what the "real" issue was. It took about two weeks, but I finally found the source one day. The source was, as silly as this may sound, her tone voice when she would ask me. She was not too far from my mothers age, and at the time I still bore a lot of resentment towards my mother. And unbeknownst to this poor lady, when she asked me to do things she just happened to ask me in an identical voice tone that which my mother used with me as child. She came off sounding very condescending. Once I found the source of the problem I was able to deal with it and move on, and no longer respond in anger when she asked me to do something.