This takes two minutes or less and can help calm you when you are feeling very stressed.
Sit comfortably, back straight, eyes closed, and take a very deep breath in through your nose. Hold for a couple seconds and breathe out of your mouth. Now, without breathing In again bend your chest forward towards your lap to finish emptying your lungs completely. Then, slowly sit back up and breathe in deeply again. Finally, as you exhale this time, slowly open your eyes.
Feel the lightness? Feel refreshed? Namaste.