There is a beginning and a middle and an end

You have to stop in the beginning before you react so you can decide what is the best way to react. Because if you don't you sure won't stop in the middle once you are reacting. And in the end you won't be able to stop the consequences for how you reacted. And let's face it your first reaction to something happening that is negative is very negative. So unless you want it to have a negative outcome for you in the end you need to stop and think about what your actions will bring. The outcome of the situation is determined by how you react to your situation not the situation itself.