You can take a deep breath anywhere and at any time. Take a deep breath until you feel your lung is filled with fresh air (Chinese version is not accurate -- translator), which makes you feel happy and alert.
* 做深呼吸
不論在何時何地都可以做深呼吸。深吸一口氣,直到感覺肺部已充滿了氮氧化物,這種物質可以使人更加開心,更加警覺。
(Chinese version from internet)
More references
Benefits of Deep Breathing
http://www.livestrong.com/article/92264-benefits-deep-breathing/