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!
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 are willing to give 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.
Holding a grudge can make you a bitter person. Letting it go is forgiving yourself for allowing these negative feelings into your life, freeing you up to move forward in your life.