According to a recent study - HERE'S A LINK - praying reduces anger by allowing you to view situations from a new perspective. This new perspective allows you to take things less personally and experience empathy for others.
In one of the experiments subjects were asked to rank their feelings (including anger), and then write about an event that had made them angry recently. Afterwards they were told an unseen partner would evaluate the essay. There was no partner; however, and the participants received very negative evaluations with comments like, "This is one of the worst essays I have ever read!"
After being angered, the students were asked to read an article about a student with a rare form of cancer and think about her situation. Then half of the participants were asked to think about the student for five minutes and the other half were asked to pray for the student for five minutes.
The participants who prayed were significantly less angry than those who simply thought about the student.
I don't mean to present this as proof that God exists, but I also don't mean to present this as proof that He DOESN'T exist. I think that for those of us who believe in God, this is another example that in addition to divine intervention, following His counsel and commandments can also have immediate, natural consequences that bless our lives.
So, say a prayer. Pray for your family, or the person who angered you and you'll find that the feelings of resentment will fade away and leave you with a more accurate view of the world.
“Anger will never disappear so long as thoughts of resentment are cherished in the mind. Anger will disappear just as soon as thoughts of resentment are forgotten.” -- Buddha