When I last saw the Venerable Ji Xing speak (in 2009), he uttered a well-known quotation that caught my attention. It is simple; "Don't let someone you hate 'rent a room' for free in your mind!" When you let that occur, someone can 'remote control you' from wherever they happen to be.
The Venerable also told an interesting story about a blustery person who came to visit him to seek advice, who quickly became angry with the questions he asked. To this the Venerable replied, "A child in primary school knows how to be happy . . . ". At this, the person visiting him became even angrier, until they finally understood that simply being happier was so much simpler.
In short, be free of hatred and anger, as they part of the root of all suffering. In one final comment one the subject, he had everyone in the room do a simple exercise; "Look to your right, and pat the person next to you. Tell them, it is okay, you should not suffer anymore. Then look to your left, and do the same thing. Finally, take both your hands and pat yourself on your shoulders, 'It is okay, you should not suffer anymore'."
May all beings be happy!