The reward for diligent use of the means of grace is great:
"We learn, in the last place, from these verses,the importance of a diligent use of religious privileges. What says our Lord? "Unto you that hear shall more be given. He that has, to him shall be given--and he that has not, from him shall be taken even that which he has." This is a principle which we find continually brought forward in Scripture. All that believers have is undoubtedly of grace. Their repentance, faith, and holiness, are all the gift of God. But the degree to which a believer attains in grace, is ever set before us as closely connected with his own diligence in the use of means, and his own faithfulness in living fully up to the light and knowledge which he possesses. Indolence and laziness are always discouraged in God's word. Labor and pains in hearing, reading, and prayer, are always represented as bringing their own reward. "The soul of the diligent shall be made fat." (Prov. 13:4.) "An idle soul shall suffer hunger." (Prov. 19:15.)
Attention to this great principle is the main secret of spiritual prosperity. The man who makes rapid progress in spiritual attainments--who grows visibly in grace, and knowledge, and strength, and usefulness will always be found to be a diligent man. He leaves no stone unturned to promote his soul's well-doing. He is diligent over his Bible, diligent in his private devotions, diligent as a hearer of sermons, diligent in his attendance at the Lord's table. And he reaps according as he sows. Just as the muscles of the body are strengthened by regular exercise, so are the graces of the soul increased by diligence in using them.
Do we wish to grow in grace? Do we desire to have stronger faith, brighter hope, and clearer knowledge? Beyond doubt we do, if we are true Christians. Then let us live fully up to our light, and improve every opportunity. Let us never forget our Lord's words in this passage. "With what measure we use;" to our souls, "it shall be measured to us again." The more we do for our souls, the more shall we find God does for them."
J.C. Ryle, Expository Thoughts on the Gospels. (Monergism Books, Kindle Edition). From his exposition of Mark 4:21-25.