John Chrysostom

This must everywhere be our concern, not simply to pray but to pray in such a way as to be heard. It is not sufficient that prayer effects what is intended, unless we so direct it as to appeal to God. For the Pharisee too prayed and achieved nothing, and again the Jews prayed but God turned away from them in their prayer. They did not pray, you see, as they should have prayed. Hence we were bidden to pray the prayer most likely to be heard.… Being heard happens in this fashion: first, of course, worthiness to receive something; then, praying in accordance with God's laws; third, persistence; fourth, asking nothing earthly; fifth, seeking things to our real benefit; sixth, contributing everything of our own.