Why? How? I am my own problem!

I love the model and I have been using them a lot lately! Yesterday I had a terrible day. My teenage sons were fighting and I lost my cool. Then my other son (I have four) lied to my husband and me – it was a big lie. To top it off, I felt overwhelmed with schedule changes. I tried to pull away and model my thoughts because they were all negative. But I found myself indulging in being angry. I felt like my anger and frustration were justified. I felt more more drawn and compelled to stay negative than create a change in my thoughts to think differently. Why?? My thoughts and feeling were not serving me but I seemed to want to stay in the negative and the anger. Is it that I have not strengthened my positive thinking muscles enough and my default is usually to be negative? What is a good technique to interrupt the tendency to self-indulge?