“Who is praying for you as you preach? Have you recruited anone to support you through the ministry of prayer? Do you keep them informed of your sermon themes and the needs of your listeners so that they can pray more meaningfully?
Spurgeon was once asked the secret of his preaching power. In answer, he took the inquirer down to the ‘engine room’ of the church, where more than five hundred people were praying for the sermon half an hour before the service began.”
Kenton C. Anderson, in Choosing to preach: A comprehensive introduction to sermon options and structures.