Quoting CS Lewis:
To forgive the incessant provocations of daily life - to keep on forgiving the bossy mother-in-law, the bullying husband, the nagging wife, the selfish daughter, the deceitful son - how can we do it? Only, I think, by remembering where we stand, by meaning our words when we say in our prayers each night, "Forgive our trespasses as we forgive those who trespass against us.
Source: Johann Christoph Arnold - Why Forgive?, pp.123