"Faith puts forth an assisting act in prayer. And it does this in two ways. First, it assists the soul with persistence. Faith is the wrestling grace. It comes up close to God, reaches out to Him, and will not easily take a denial. Faith is the soul's eye by which it sees the filth and hell in every sin. It is this insight, which makes the heart sorrowful when the soul spreads its abominations before the Lord. Tears come as freely as water from a flowing stream when faith finds Jesus in His love and graces reflected in the mirror of promise.
Never before could the Christian know what to do with a promise in prayer until faith teaches him to press in to God with it, humbly yet boldly. "What wilt thou do unto thy great name?" asks believing Joshua Joshua 7:9. It is as if he had said, "You are so inseparably bound to Your people by promise that You cannot leave them to die unless Your name suffers with them."
The second way faith assists in prayer is that it empowers the soul to persevere. As the wheel wears out with turning until it breaks, the hypocrite prays until he gets tired. Sooner or later something will make him abandon the duty, which he never really liked anyway. But it is impossible for the sincere believer to stop praying unless he also stops believing. Prayer is the very breath of faith. Stop a man's breath and where is he then?
Are you compelled to pray? As a baby cannot help but cry when it is hurt or wants something-- because there is no other way to get help-- so the Christian's wants, sins, and temptations return to him and he cannot do anything but pray about them. "From the end of the earth will I cry unto you," says David Psalm 61:2. He was saying, "Wherever I am I will find You. Imprison me, banish me, or do with me what You will-- You will never be rid of me." "I will abide in your tabernacle forever" Psalm 61:4.”Quoted material from, ”The Christian in Complete Armour Daily Readings in Spiritual Warfare” by Gurnall and James S Bell. http://www.moodypublishers.com/pub_productDetail.aspx?id=41823&pid=53617