Joy is something very deep and profound, something that affects the whole and entire personality. In other words it comes to this; there is only one thing that can give true joy and that is contemplation of the Lord Jesus Christ. He satisfies my mind; He satisfies my emotions; He satisfies my every desire. He and His great salvation include the whole personality and nothing less, and in Him I am complete. Joy, in other words, is the response and the reaction of the soul to a knowledge of the Lord Jesus Christ. (Life in Christ, 30)
MacArthur, John F. 1-3 John MacArthur New Testament Commentary (Macarthur New Testament Commentary Serie) (p. 20). Moody Publishers. Kindle Edition.