"When you forgive, you are promising to no longer hold your offender's trespasses against him.
You are also promising to impute your forgiveness to him
(much like Christ imputed His righteousness to you when you became a Christian).
The dictionary defines the verb 'impute' as follows:
(1) 'to charge with the fault or responsibility for';
(2) 'to attribute or credit.'
When you promise not to impute your offender's trespasses against him,
you are promising to no longer charge him for what he has done.
This means you are not going to allow yourself to dwell on the offense.
You will refuse to cultivate those seeds of hurt, but rather will immediately pluck them out of the soil of your heart."

[Lou Priolo, "Bitterness"]