You therefore must be perfect, as your heavenly Father is perfect.
Mt. 5:48
The seemingly impossible call to be perfect is preceded by the how. Love my enemies.
Loving even my enemies seems impossible, which it is without grace from God. It starts with me deciding to wish the good of others. This not only benefits my enemies, it benefits me.
My response to injury from others can be that of Saint Stephen. Lord, hold not this sin against them. That prayer drains the poison of resentment and revenge.
Jesus, help me be perfect as my heavenly Father is perfect.