Without extended, concentrated prayer, the ministry of the Word withers. And when the ministry of the Word declines, faith (Rom. 10:17; Gal. 3:2, 5) and holiness (John 17:17) decline. Activity may continue, but life and power and fruitfulness fade away. Therefore, whatever opposes prayer opposes the whole work of ministry.
John PiperI know of no other way to triumph over sin long-term than to gain a distaste for it because of a superior satisfaction in God.
John PiperThere are only three kinds of Christians when it comes to world missions: zealous goers, zealous senders, and disobedient.
John PiperFeeling loved by God means feeling glad not only that He crushed His Son so that I can be forgiven, but that He's crushing everything that takes away from my praising of the glory of His grace.
John Piper