We know the scriptures command us to forgive. Here's a passage from Matt 18: 

The Parable of the Unforgiving Servant
21 Then Peter came to Him and said, "Lord, how often shall my brother sin against me, and I forgive him? Up to seven times?" 
22Jesus said to him, "I do not say to you, up to seven times, but up to seventy times seven. 23Therefore the kingdom of heaven is like a certain king who wanted to settle accounts with his servants. 24And when he had begun to settle accounts, one was brought to him who owed him ten thousand talents. 25But as he was not able to pay, his master commanded that he be sold, with his wife and children and all that he had, and that payment be made. 26The servant therefore fell down before him, saying, "Master, have patience with me, and I will pay you all.' 27Then the master of that servant was moved with compassion, released him, and forgave him the debt. 
28"But that servant went out and found one of his fellow servants who owed him a hundred denarii; and he laid hands on him and took him by the throat, saying, "Pay me what you owe!' 29So his fellow servant fell down at his feet and begged him, saying, "Have patience with me, and I will pay you all. 30And he would not, but went and threw him into prison till he should pay the debt. 31So when his fellow servants saw what had been done, they were very grieved, and came and told their master all that had been done. 32Then his master, after he had called him, said to him, "You wicked servant! I forgave you all that debt because you begged me. 33Should you not also have had compassion on your fellow servant, just as I had pity on you?' 34And his master was angry, and delivered him to the torturers until he should pay all that was due to him. 
35"So My heavenly Father also will do to you if each of you, from his heart, does not forgive his brother his trespasses."

None of us wish to wind up like this unforgiving servant above. The first thing this passage does for me, and did for my husband as well, is to be able to forgive. If I can be forgiven of all my transgressions, who am I not to forgive? It doesn't matter if my transgressions were "worse" or "less than" the offenses toward me. In our Father's sight, we are ALL sinners, and He won't tolerate sin in His presence. 

So, HOW do we forgive? It's not easy. But, if we have the desire to obey the Father, that is a good motivator.   We must remember that to forgive is a choice, it is not a feeling.  We may not always feel the forgiveness or feel like forgiving, but choosing to do so means choosing obedience to the L-rd. 

Faith comes by hearing, and hearing by the Word of G-D. (Romans 10:17 )There is scientific evidence that the more our outer ear hears, there is information sown into the inner ear and the mind is able to retain it and even believe it. That is why we are encouraged to read out loud. So, this next exercise is important to do "out loud" even if just slightly audible, you need to be able to hear yourself say this.  Especially if your are struggling with the wanting to forgive part.  The more you hear yourself say “I forgive” the more you will believe it yourself!

There is also a spiritual reason to say the following out loud. You are making a declaration before the L-rd and before the spiritual realm of which we can not see, that you are acting in obedience and out of faith to forgive the person. Spiritually, this cancels seeds of un-forgiveness that are tried to be sown in your relationship with the person
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I'm always concerned someone will think I'm a spiritual nut. Be it as it may, I was delivered from a very powerful spiritual life/realm. I was raised in a home of witchcraft and practiced new age myself before being saved. I also have experienced a lot of spiritual encounters since knowing the L-rd. I believe because I knew how the spirit world worked from the other side before being saved, that the L-rd allows me to deal with spiritual/demonic deliverance in people's lives. Seeds of un-forgiveness are some of the most powerful tools that Satan uses. Just re-read the above passage from Matt. The Father says if we do not forgive in our hearts, He will not forgive us. What better way for the enemy to keep people out of the kingdom of heaven? I have seen folks refuse salvation for the very reason that they could not accept that the L-rd forgave folks who sinned against them. Un-forgiveness is not just a feeling/sin nature. It is also a tool of the enemy. 

So we should also ask the L-rd to cleanse our homes of all unrighteousness. Renounce and repent of any un-forgiveness in your life. Ask the L-rd to bind any spirit that is not of Him, and cast it far from you. Ask that only the L-rd reign in your home, mind, and heart. Pray for protection from a spirit of un-forgiveness and pray for help to take every thought captive unto the obedience of Christ should an unforgiving thought arise in the future. You may have to work on this last one for a long time.  Do it as long as it takes, we must persevere, remember, we’re soldiers marching in a spiritual war.

1) Imagine you can see whoever you need to forgive and imagine you placing your hands on each of their shoulders, and look them in the eye (again, you are imagining this-because it is an "exercise" someday if you wish to do this face to face, you have that freedom.)  Once you feel a release in your spirit that you have fully forgiven, there is no need to repeat this exercise

2) Say out loud "__________,(person’s name) I forgive you for all that you have done to me. " 
3) Say out loud "I love you with the love of Jesus" 

4) Say out loud " and I bless you with G-D's richest blessings" 

5) this is tricky: MEAN IT WITH ALL OF YOUR HEART. 

The only way you can accomplish #5 is to recite the exercise over and over because the more you "hear" it, the more you will believe it. Remember, this is also an act of obedience to the Father. He will honor your efforts and meet you where you are at. Ask Him to help you to mean it. 

I was given this exercise from my "spiritual mother" who also uses this herself. When a sister in the L-rd wrongs her in some way, she has used this. When she has come across a difficult situation, she used this. She one day had to repeat this to herself while ironing about 100 times. Other incidents required days of her doing this until she felt a release from the burden she would carry toward the person. 

I now use this myself. I do finally sense a relief when I follow through with this program. I realize it isn't always a feeling. It's an act, and I choose to forgive. 

May G-D bless you on your road to forgiveness!!! Your load will be much lighter!