Today's gospel was particularly illuminating and helpful, the gist of it being this post's title. Basically, it means that while it's normal for us humans to feel anger, even hatred, we should avoid cursing or directing our anger towards the person who's hurt / harmed us in whatever way.
Instead, it's better (for everyone concerned) that we focus our anger on the sin itself and just pray for that person (well, actually, we're asked to LOVE the sinner but if this isn't possible then we can simply pray for him / her instead) to change or realize his / her mistakes.
Now, there are also times when we just NEED to release our anger. Maybe because we feel so hurt, betrayed, wronged - the reason doesn't really matter. Sometimes, we just feel the urge to release our anger. Well, this, too, is normal, and if you're feeling like this, Fr. E advises us to purge our anger simply by writing everything we feel and turn our hate into words on paper. And once it's done, crumple that piece of paper into a ball, and throw it away...along with your anger and hatred.
So yeah, bottom line is...let it go, don't hate, and focus on the positive. It's a tall order, as all of God's teachings are, but I definitely see the merits in it, and I feel - with regular practice - it will go a long way in making life better for us in the long run. We'll all be happier this way and find it easier to get along.