This is the mark of Christianity: However much a man toils, and however many good deeds he performs, to feel that he has done nothing, and in fasting to say, “This is not true fasting,” and in praying, “This is not true prayer,” and in perseverance at prayer, “I have shown no real perseverance; I am only just beginning to practice and to take pains”; and even if he is righteous before God, he should say, “I am not righteous, not I; I do not take pains, but only make a beginning every day.”
-St. Macarius the Great (4th c.)
Praying With My Feet 