Resentment

"If you have a resentment you want to be free of,
if you will pray for the person or the thing that you resent,
you will be free. If you will ask in prayer for everything
you want for yourself to be given to them, you will be free.
Ask for their health, their prosperity, their happiness, and you will be free.
Even when you don't really want it for them,
and your prayers are only words and you don't mean it,
go ahead and do it anyway. Do it every day for two weeks
and you will find you have come to mean it and to want it for them,
and you will realize that where you used to feel bitterness and resentment
and hatred, you now feel compassionate understanding and love."

from p. 552 of Alcoholics Anonymous, the Big Book of AA