When you stand to pray, forgive anyone against whom you have a grievance, so that your heavenly Father may in turn forgive your transgressions. (Mark 11:25)
The Lord Jesus exhorts us to pray with boundless confidence. He wants us to believe that our heavenly Father loves us so much that He will give us whatever we ask for. Boundless faith—the faith of a true friend and intimate of God—this opens the door of prayer.
Christ is talking to zealous believers here—prayer warriors, confirmed disciples.
At the end of this discourse, He slips in a wonderful little nugget: ‘You lovely, holy saints-in-the-making, beloved intimates of Mine, My chosen ones: remember that you stand guilty of transgressions against God.
‘Just like everybody. Just like the tax collector hunched over in the back of the Temple I just cleansed.’
With this little, last-minute reminder, the Lord shows us the way into His Heart. We enter His Heart when we acknowledge our solidarity with the sinful mass of human flesh, of which we form our part.
It is not for me to wonder if I am a sinner or not. I know that I am one. I pray, Lord, that You might enlighten my mind, so that I can know my sinful self better. I know that You forgive.
We Catholics don’t believe in magic. But one thing that works like magic is this:
I resent something someone else has done. I can’t bring myself to forgive.
I turn my mind from the business altogether. Instead, I say to the Lord: ‘Lord, I believe with all my heart that I have done wrongs which put You on the cross, even though I don’t even know the half of them. You suffered for me, and I praise You and bless You, and I admit that if I spent every minute of every day of my life thanking You for what You did to save me from the hellfire I deserve—it wouldn’t be anywhere near enough.’
I say this, and presto! Not as angry at the other guy as I was.
Father Mark White Blog 
I am putting my thoughts about the squirrel trying to get sustenance from the bird feeder here since I may be transgressing. If you picture Moi as the squirrel and STEP and Helping Hands as the feeder you would have the true picture of what occurred. Picture all my taxes for the past 40 years paying for the feeder and the sunflower seeds; nevertheless I am flung. Plus which, all the seeds that were spilled could have fed ten squirrels.