“… when a man prays, He strengthens his heart by faith and by the hope of receiving that which he prays for. He inflames the soul with love to God; He fills the soul with bright, good thoughts, strengthening the mind and heart. If the man has any work to accomplish, He strengthens his heart by the conviction of the importance and the necessity of his labor, and by an invincible patience which overcomes all difficulties.”
(St. John of Kronstadt in ‘My Life in Christ’  on the work of the Holy Spirit)