Why have I been so aggressive lately?

I don’t understand but for a long while I have been actually wanting to get into a fight. To start one or to be involved in one. I’m not sure what action or event in my life triggered this but I just can’t seem to stop thinking about it. I watched Fight Club last night, thinking it might ease my desire to have a physical altercation but it didnt. I box and when I do, I’m not quite as eager to argue or snap but I want to understand why I’m this way at all. I have always been the kind of person who couldn’t stand hurting others or even confrontational arguments. This is so out of nowhere.