A Christian should carry the weapon of all-prayer like a drawn sword in his hand. We should never sheathe our supplications. Never may our hearts be like an unlimbered gun, with everything to be done to it before it can thunder on the foe, but it should be like a piece of cannon, loaded and primed, only requiring the fire that it may be discharged. The soul should be not always in the exercise of prayer, but always in the energy of prayer; not always actually praying, but always intentionally praying.(The Parables of Our Lord [Grand Rapids: Baker, reprint 1979], 434–35).
MacArthur, J. F., Jr. (1995). Alone with God (16). Wheaton, IL: Victor Books.