Think of a person who has hurt you and apply the steps to REACH forgiveness
Recall the Hurt. When we are hurt, we often try to protect ourselves by denying our hurt. We think, often correctly, that if we don't think about it, it won't bother us. But if unforgiveness keeps intruding into your happiness or gnawing ulcers in your gut, consider forgiving. Recall the hurt as objectively as possible. Don't rail against the person who hurt you, waste time wishing for an apology that will never be offered, or dwell on your victimization. Instead, admit that a wrong was done to you and set your sights on its repair.
Empathize. Empathy involves seeing things from another person's point of view, feeling that person's feelings, and identifying with the pressures that made the person hurt you. To empathize with your offender's experience, write a brief letter to yourself as if you were the other person. How would he or she explain the harmful acts?
Altruistic gift of forgiveness. Empathy can prepare you for forgiving, but to give that gift of forgiveness, consider yourself. Have you ever harmed or offended a friend, a parent, or a partner who later forgave you? Think about your guilt. Then consider the way you felt when you were forgiven. Most people say, 'I felt free. The chains were broken.' Forgiveness can unshackle people from their interpersonal guilt. By recalling your own guilt and the gratitude over being forgiven, you can develop the desire to give that gift of freedom to the person who hurt you.
Commit to forgive. When you forgive, you can eventually doubt that you have forgiven. When people remember a previous injury or offense, they often interpret it as evidence that they must not have forgiven. If you make your forgiveness tangible, you are less likely to doubt it later. Tell a friend, partner, or counselor that you have forgiven the person who hurt you. Write a 'certificate of forgiveness,' stating that you have, as of today, forgiven.
Holding onto forgiveness. When you have doubts about whether you have forgiven, remind yourself of the Pyramid, refer to your certificate of forgiveness, and tell yourself that a painful memory does not disqualify the hard work of forgiveness that you have done. Instead of trying to stop thoughts of unforgiveness, think positively about the forgiveness you have experienced. If you continue to doubt your forgiveness, work back through the Pyramid.
Any other useful additional information
Evidence that this works (from Authentic Happiness):
In the largest and best done study of REACH to date, 259 adults were randomly assigned to either 6 90 minute forgiveness workshop sessions or to an assessment only control group. Less anger, more stress, more optimism, better reported health and more forgiveness ensued, and the effects were sizeable.