Our Scripture reading today is Matthew 6:9-13.
Verse 12, "And forgive us our debts, as we forgive our debtors."
The Sermon on the Mount offers much to be gained for the disciple of the Lord Jesus.  We have the greatest preacher delivering truths that equip us to live properly in this sin cursed world.  Forgiveness is an opportunity for us to be like Jesus Christ.  In His humility, Jesus offers us forgiveness full and free.  When we forgive, God sees His image in our lives. 
The sinless, Son of God willing forgives sinners like you and me.  As we meditate on that truth, it should become less complicated for we sinners to forgive other sinners.  Mark 11:25-26, "And when ye stand praying, forgive, if ye have ought against any: that your Father also which is in heaven may forgive you your trespasses. But if ye do not forgive, neither will your Father which is in heaven forgive your trespasses."  When we withhold forgiveness we are not only disobedient, we are also only making worse regarding the offence that took place.  The longer I refuse to forgive, the greater opportunity for bitterness to take root.  Our God sets the example in Psalm 86:5, "For thou, Lord, art good, and ready to forgive; and plenteous in mercy unto all them that call upon thee."