One thing from A Generous Orthodoxy that positively challenged me were some of McClaren's thoughts on prayer. He critiques the perception that an unwritten, unprepared prayer is more "from the heart" than a written, planned one. However, we often hear more stuttering nervous ticks (God just help us, just now God) than something of value or meaning. So, while spontaneous prayer should not part from us, we should probably give more attention to the words which exit our mouths. J.P. Moreland discussed in Love Your God With All Your Mind that we are sometimes so unattentive in our own prayers that we will utter heresies unawares. ("Our Father, we're glad you came to earth to die for us." Welcome to Modalism.)
How can we be more sincere in our prayer? Can prayer be heartfelt and planned at the same time?