Resentment

While going through the quotes of Gauthama Buddha, one of his quotes struck me,

Anger will never disappear so long as thoughts of resentment are cherished in the mind. Anger will disappear just as soon as thoughts of resentment are forgotten.- Gauthama Buddha

It really struck me, as there is a thin chord attached to me. I am usually one of person who gets angry fast, its just like the mercury, bouncing on when there is a temperature rise, but i cool down as well as mercury when out of situation. What Buddha would have told the world, On how to forget the resentment?