What would you do?

What do you do when you find yourself acting in a way you don't like? Yesterday I spent most of the afternoon mad at my friend Josh, for something that was so stupid that normally it wouldn't have bothered me at all. In reality, I was upset with someone else, and with other situations in my life in general, but Josh was here, so I unfairly took it out on him.

I apologized to him this morning, and he said it's OK, but I still don't feel good about how I treated him yesterday. I know at this point I can't do more than apologize and move on, which I've already done. I'd like to figure out a way to keep this from happening in the future. (with anyone, not just with Josh.)