Overcome Anger or Fear

The use of a mantra, or prayer word, allows us to channel our energy toward our divine nature. When negative mind states arise such as anxiety, anger, or fear we can use the energy of these emotions in a positive way through introducing the mantra into the mental field. The “fire” or energy of the emotion then becomes a transforming fire instead of a destructive fire.
~Yogacharya Ellen Grace O'Brian

Mantra is a sacred sound or word formula that creates a vibration that supports us to get beyond our thinking mind. A mantra can be as simple as the repetition of the word love or peace. Something that resonates with us. Many traditions have a form of mantra. Paramahansa Yogananda taught the mantra Hong Saw. It doesn't have a particular meaning, but allows us to focus our attention inward as we repeat Hong on the in-breath, and Saw on the out-breath. We can say it to ourselves as we begin our meditation, using it as our point of focus. The vibration of the word formula allows us to move from the state of concentration to the state of meditation. 
As we use the same mantra over and over, it can resonate in the back of our mind even when we are not sitting to meditate. When negative emotions arise we can then use the tool of mantra to burn them away.