• Understand why. We want explanations—even if we don't agree with them. "Was it a misunderstanding? Were you mad at me? Some sort of cognitive framework is necessary, even if you don't like the reason (she was just a selfish jerk)," Howes says.
• Rebuild safety. Before you forgive, you need to feel reasonably sure that the act won't reoccur. That might mean an apology, reassurance from the person in question, distance, or stronger boundaries.
• Let go. Perhaps it's the hardest part: making a conscious decision not to hold a grudge. If you're in a relationship, this means not bringing up past transgressions. By letting go, you give up your role as the victim and become equals again. It's a promise to yourself to stop ruminating and to fully move on.
When you feel upset, try a stress-management technique, like deep breaths or a yoga session, adds Luskin.
No matter how you go about it, choosing to forgive will likely prove a worthwhile endeavor. About a decade ago, Luskin did a research project with a group of mothers whose sons had been murdered in northern Ireland. One woman had been searching for her son's body since 1987. Luskin spent a week teaching the women how to forgive the person who had murdered their child. A year later, he reunited with the entire group. "The daughter of one of the women came up and hugged us, and thanked us for giving her her mother back," Luskin says. "The mother had been so consumed with anger that she was never able to be there for her other children. But she finally learned to forgive, and her daughter said, 'We have a mother again.'"