In the practice of the six yogas of Naropa, a process called “dispelling the impure winds through the nine rounds of breathing” is explained: First one inhales through the right nostril and exhales through the left, then one inhales through the left and exhales through the right. First close the left nostril with the back of your right index finger and inhale through the right nostril, and then exhale from the left nostril while blocking the right nostril; after that, block the right nostril with your left index finger and so forth. During this process, although in reality you are inhaling and exhaling through the nostrils, imagine that the winds come out and go in through the two side channels. One can also do the practice without blocking the nostrils by hand.
This will calm the force of whatever emotion you have, because it prevents reinforcement of it. The strong force of emotion calming down is just like turbid water becoming clear. A nonvirtuous state of mind should be transformed to a neutral one and then skillfully transformed into a virtuous state.
Adapted from The Union of Bliss and Emptiness: Teachings on the Practice of Guru Yoga by The Dalai Lama