I learned this not long ago, because I felt that God put it on my heart. Forgiveness is very difficult. I struggle with this especially for those I know are evil. But it is necessary so that it does not consume you, but more importantly, it allows you to live in His holiness.
I was stubborn because I never allowed myself to really hear those words. But then one day I had ears to hear them and it caught on.
Try your best to live in God's holiness as best you can. Live a Christ-like life to the best of your ability.