Gratitude
Too often, like the Children of Israel, our human tendency is to quickly go from gratitude for an answered prayer right back to ingratitude. Because of this, I believe God will sometimes allow us to go through an “I will never forget that” sort of trial before granting the deliverance for which we are praying. Even then, we must be careful to guard against a complaining spirit by purposely looking back to that great deliverance.