It is true that anger and strife are in the nature of the human vital and do not go easily; but what is important is to have the will to change, and the clear perception that these things must go. If that will and perception are there, then in the end they will go. The most important help to it is, here also, for the psychic being to grow within—for that brings a certain kindliness, patience, charity towards all and one no longer regards everything from the point of view of one’s own ego and its pain or pleasure, likings and dislikings. The second help is the growth of the inner peace which outward things cannot trouble. With the peace comes a calm wideness in which one perceives all as one self, all beings as the children of the Mother and the Mother dwelling in oneself and in all. It is that towards which your sadhana will move, for these are the things which come with the growth of the psychic and spiritual consciousness. Then these troubled reactions to outward things will no longer come.
Ref : Letters on Yoga Vol. III