Our brains are not quite as advanced as we would like to believe they are. We can only focus our attention on one thing at a time. So if we want to interrupt our automatic reaction in a situation and handle it differently, focusing on our breathing, even if it is just for one breath, will give us enough time to choose our response.

Often I find myself taking more than one because I need a bit more time to disconnected from my usual reaction. Don't worry about what the other person is thinking. If you breathe for a long enough time they will certainly ask what you are doing. Your answer will either be, "I am listening to what you are saying," or "I am thinking about how to respond."