If you feel stressed out and overwhelmed, breathe. It will calm you and release the tensions. If you are worried about something coming up, or caught up in something that already happened, breathe. It will bring you back to the present.
If you are discouraged and have forgotten your purpose in life, breathe. It will remind you about how precious life is, and that each breath in this life is a gift you need to appreciate. Make the most of this gift. If you have too many tasks to do, or are scattered during your workday, breathe. It will help bring you into focus, to concentrate on the most important task you need to be focusing on right now.