Prayer, if it is in any sense to be "meaningful", must be an encounter with the "real" God. The real God can be frightening. If you have never stood before God and been terribly afraid, then you have never stood before God. He isn't safe, He isn't always nice, He isn't accommodating, and He isn't in the business of making us feel comfortable with our rebellion.
Steve Brown, Approaching God: How to Pray, 21.