"But I tell you who hear me: Love your enemies,
do good to those who hate you, bless those who curse you,
pray for those who mistreat you" (Luke 6:27-28).
Even when we say, "I forgive you," many of us have a difficult time not thinking about what others have done to hurt us... It is very difficult simply to stop thinking about an unpleasant experience. Instead, we must replace negative thoughts and memories with positive ones... Every time you begin to dwell on or brood over what someone else has done, ask for God's help and deliberately pray for that person or think of something about the offender that is "true, noble, pure, lovely, admirable, excellent, or praiseworthy."
Taken from The Peacemaker: A Biblical Guide to Resolving Personal Conflict
by Ken Sande, Updated Edition (Grand Rapids, Baker Books, 2003) p. 220-221