"In order to avoid emotional disturbance, it is important to know how to react to people and circumstances. Where there is happiness, one should be friendly; where there is misery, one should be compassionate; where there is virtue, one should rejoice; and where there is wickedness, one should be indifferent. Any other kind of reaction - for example, jelousy, anger, indignation or resentment - does not engender peace.
Thoughts, emotions and deeds that go against ethical precepts result in pain and ignorance. They are caused by greed, anger and delusion. These negative states of mind lead to unpleasant consequences, which unsettle the mind further. They need to be checked by the practice of Yoga."
(Yoga - The Iyengar Way, Silva, Mira & Shyam Mehta)