Open your heart. As Daniel Goleman writes in Social Intelligence, "Empathy is the prime inhibitor to human cruelty." Only when we see our enemies as individuals deserving empathy can "the war between Us and Them ever stop." We tend to demonize those who hurt us. But when we work at understanding our foes to be struggling, imperfect people — just like us — capable of making mistakes, we make room for empathy to be stirred in our shut down hearts.
And open your eyes. Trust is a delicate creature, however. We're smart to remain vigilant, savvy and history-smart in re-establishing trust with someone who has hurt us. Remember, forgiveness contains a degree of wisdom (otherwise, it's not forgiveness).
See also: Words of Wisdom From Bill Gates
Turn it over. Wisdom, by definition, means relinquishing control over final outcomes. Would-be forgivers are often blocked by the fine print of their own expectations ("I will forgive only if this happens…"). But that is not how forgiveness works. Surrendering a measure of personal will (in the sense of Thy will be done, whether the Doer is a divine entity or fate itself) allows both parties to regroup and begin anew.
Stay strong. Just as we cannot move forward and be dishonest at the same time, we cannot remain petty and hope to expand beyond the level of personal grievance. Mired down by the letter of the law, we may lose the spirit of forgiveness. This spirit derives from a desire for justice but also from a pull toward personal happiness. Held hostage to rigid ideas about right and wrong, or should and shouldn't, we cannot hope to resolve our conflicts with an open mind. As a survivor of the Holocaust wrote, "You must be strong to forgive. Forgiveness is not about condoning or excusing. Forgiveness has nothing to do with justice. Forgiving is a selfish act to free yourself from being controlled by your past."
And who doesn't want that?