Alistair's posts are awesome, if a bit long.
As for me, I am angry at the girl I was working with tonight, because she is exceedlingly slow at cleaning so we got out an hour late. That's 10.30pm at night. Stupid, and it's happened twice.
I get on my soapbox about this about once a year. Get angry with me if you want, I don't care.
It is important to remember that Hinton did not cause go123 to become angry nor did that slow cleaner cause pianochick to become angry.
What really happened is that go123 and pianochick chose to become angry at somebody else's actions, ceding control. And they could just as easily have chosen not to become angry, which would have accomplished two things: not having to feel upset, and being able to cope better in a practical sense. Almost never does our anger help us think more clearly.
She's cleaned slowly twice before, yet you failed to expect it? Shame on you for being surprised, it was completely predictable. You knew it was going to happen, you chose to do nothing about it, then you chose to get angry at her. It's not stupid, it's reality.
I'm being more direct than usual, this could possibly be said more tactfully. But I'm not going to force you to react either way!
There are some specific techniques that make it easier not to get unnecessarily angry. Ellis's RET is one of the more successful ones.