Forgiveness is an interesting dynamic. Some people are naturally inclined to forgive and others refuse to forgive even the slightest offense. (Some even create offenses where none exist!) As Christians, we have many aids to forgiveness, but it needs to be understood that these are not methods to bolster our natural tendency to forgive. They are the means of forgiving when those natural tendencies have failed. I will lay these out as steps.
Step One: Confess to God that you are completely unable to forgive on your own. This is a vital first step. The words "I can't...but You can" can be tremendously freeing. (Matthew 5:3)
Step Two: When we come to God for help in forgiving others, we often end up being the recipient of all kinds of insights from God about OURSELVES. He uses our need to highlight our own limitations and heart conditions. We come to realize with His help that, although we've truly been hurt, we're not entirely the victim. When those revelations come, however unwelcome, we need to be quick to bring them before the Lord and confess them as sin. Being free to forgive others is just as much about being right with God OURSELVES as it is getting past the hurt.
Step Three: Focus on how much God has forgiven YOU! This may seem like a strange step...but it's absolutely HUGE. The Apostle Paul wrote: "Forgive as the Lord forgave you." Colossians 3:13b (NIV) Understanding the depth of our own sin against God is the backdrop of how God wants us to view the offenses of others toward us. In essence God is saying: "Look, I know this person hurt you...and I acknowledge that hurt. But you need to understand that the hurts you've suffered are nothing compared to the offenses you've committed against Me. I have forgiven you--completely. Now...go and do likewise in the power of my Spirit."
Step Four: This one is another vital step not to miss. Jesus said: "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 (NIV) Praying for people who have hurt us and misused us is FAR more than just a good thing to do. It sets us free! When someone hurts me I begin to pray for them, asking for God's blessing in their life. At first I don't want to do it. I would much rather ask God to pluck their eyes out! But that's my flesh talking. So I pray for the Lord to bless their life. Over time it gets easier to say the words and then after awhile something amazing happens. I find that as I'm praying for them, I actually MEAN what I'm praying. As I ask the Lord to pour out His heart and grace on that person, I find that I'm entirely genuine in my desires. It is THEN I realize that God has set me free from the resentment and bitterness of my own hurts.
A great passage to meditate on is this one:
See to it that no one misses the grace of God and that no bitter root grows up to cause trouble and defile many. Hebrews 12:15 (NIV)
A bitter root is something to be avoided at all costs! It begins by being hurt, and then justifies itself along the way by remembering and rehearsing the depth of the hurt caused. But in the end, it only serves to poison the heart of the person who entertained it.