A strong emotion is like a storm. If you look at a tree in a storm, the top of the tree seems fragile, like it might break at any moment. You are afraid the storm might uproot the tree. But if you turn your attention to the trunk of the tree, you realize that its roots are deeply anchored in the ground, and you see that the tree will be able to hold.
You too are a tree. During the storm of emotion, you should not stay at the level of the head or heart, which are like the top of the tree. You have to leave the heart, the eye of the storm, and come back to the trunk of the tree. Your trunk is one centimeter below your navel. Focus there, paying attention only to the movement of your abdomen, and continue to breathe. Then you will survive the storm of strong emotion.
You should not wait for emotion to appear before you begin practicing. Otherwise, you will be carried away by the storm. You should train now, while the emotion is not there. So sit or lay down and practice mindfulness of the breath, using the movement of your abdomen as the object of your attention. I am positive that if you do this exercise for twenty days, ten minutes per day, then you will know how to practice whenever a strong emotion comes up. After ten or twenty minutes, the emotion will go away, and you will be saved from the storm. – Thich Nhat Hanh