My first step was to convince myself that everyone is doing the best they can – at least based on the understanding they have at that moment. If your grudge is against your parents, this is especially meaningful! What I'm saying is that I had to give the person I had a grudge against the benefit of the doubt. I had to say: "What they did made perfect sense to them, even though it seems deliberately hurtful to me."
Think this first step might be a little too hard for you? Then try this. Reverse positions with the person or persons you have a grudge against. Think of something that you did in the past that made someone angry at you. Did your behavior make perfect sense to you at the time? Of course it did! Do you wish you had done something different? Probably, if you had time to think about it.
Can you see that what you were doing represented the right thing for you to do at that time? After all, you were giving expression to the level of understanding you possessed then. Maybe today you are a better, wiser, and more wonderful person. You might not respond the same way. Let's hope not. Let's hope you learned something from that experience.
The question you need to answer now is: Can you give the same kind of tolerance to the person or persons you hold a grudge against that you have just given to yourself?
Work with this question until even though you remember what happened, you cannot generate any feelings associated with the experience. When this happens, you are on your way to completely letting go of the grudge.