If you're holding a grudge or grievance against someone, let it go. Write them a letter that expresses your hurt and frustration and then tear that letter up. It's a way of physically releasing someone from their crime and spiritually freeing yourself from the burden of being angry at the same time. Take a moment afterwards to reflect on that person as a fallible human being just like you are— prone to make mistakes and in need of grace. It will help you see him or her through the eyes of God.
Author and Spirit Junkie Gabrielle Bernstein often says, "Forgiveness offers everything I want." When you forgive and release bitterness towards others, you then open up your life to receive freedom and happiness.