So what's the truth about prayer?
"Father, if you are willing, take this cup away from me—but it is not my will, but yours, that must be done.” Luke 22:42
Well the truth is not that prayer twists His arm or changes God's mind, but instead that our prayer, produced and nurtured as it is by God Himself, becomes the way by which we can enter into God's 'mind'. So we end up by asking God to do what He had always planned to do, once He had got us to the point of asking Him to do it, with a genuine belief that He would.
If we really want to see God's power at work in answering our prayers (and let's face it there would be something a bit awry if we don't), our job is not to convince ourselves of the certainty of what we've just decided to ask for will happen, just because we've decided it will... No our job in prayer is instead to ask God, to seek His will, His desires about all the needs and issues that surround us and threaten to overwhelm us; then we can allow Him to show us just how to pray within His will so that we're genuinely praying - Your will be done!