Forgiveness

There is tremendous "spiritual" power in forgiveness. Our brains/minds are powerful organisms.
When one is in the revenge mode, the mind is focussed on a highly negative response and works to create the conditions that lead to negative consequences.

Hence the old Chinese saying;
When bent on revenge, dig two graves. One for your intended victim and one for yourself.

Forgiveness however focusses the mind on the positive thus leading to desirable outcomes.

Try it. If there is someone you are angry with (y'know, you sometimes wake up in the middle of the night thinking about the wrong this person has committed, or are obsessed with their grievous wrongs against you?) and want revenge, pray for them for two weeks. Ask God, or whoever you believe in, to give them all of the things "you" want in life. Do it for two weeks and you'll be relieved of your obsession/need for revenge.