I was a really angry preteen, and although it was more manageable as a teenager, I brewed inwardly a lot.

I realized that the best way to manage it without just continuously suppressing it is to find another emotion to feel. If someone angered me, I could ask myself, "Does this hurt my feelings or am I just disappointed?" If I focused on feeling sad or hurt by a situation, I wasn't as quick to erupt or to get angry within.