Going with the flow is such an important skill that more parents need to put more of a focus in teaching. It's all about making sure that your response is a realistic way of attaining your goal in the situation.
If I'm talking to someone else and trying to help them through a situation like they say, ask them to think for a minute if getting angry will do anything at all to help the situation they find themselves in.
"You are absolutely right to be upset about this situation, and if you need to take a minute to feel that rage, go right ahead. Once you're ready though, let's take a deep breath, remember that we can't change what's already happened and instead be strategic and intentional about what we do from here to correct for what just happened"
Being able to gain control of yourself is a skill that requires practice. Intrusive thoughts and feelings and emotions happen to everyone, the trick is just recognizing when it's happening. When you recognize that it's happening, take a deep breath and shake it off. For me that means just slowing down and being much more methodical and intentional about anything that I say or do until that fight or flight mode response disengages. Be conscious of the fact that my reflexes cannot be trusted when I am in fight or flight mode.