If prayer worked by divine intervention:

Why does prayer sometimes seem to work?

Prayer is chanting, and chanting, in any form, has been proved to calm the body, which promotes healing. In fact, the near meaningless chanting of other cultures has been shown to be more effective than chanting that includes words.

Is God Real?
Is the Bible the Word of God?
Does Prayer Work?
Does Religion Belong in Government
Is the Whole World in God's Hands?
Intelligent Design?
What if God Doesn't Exist?