Ben Myers has a great post at Faith and Theology: Prayer: a little anthology. It’s all worth reading, but here are some that particularly leapt out at me.
First, a couple of quotes from John Chapman’s Spiritual Letters (memo to self: go back and finish that book!):
Two rules for praying: ‘First: pray as you can, and don’t try to pray as you can’t. And second: the less you pray, the worse it goes. (p.25)
I should prefer a bare and dry prayer, to an explosion followed by a short intoxication; because the second seems to be self-made, and therefore less pure. But I don’t dogmatise. What matters is the result. The after effects of good prayer are more definite than the prayer itself; I mean a determination to follow God’s Will, and to care for nothing else. (pp. 61-62)
Then this, from Kallistos Ware (The Power of the Name, p.19).
That is what the world needs above all else: not people who “say prayers” with greater or lesser regularity, but people who are prayers.
But above all, I love this from Karl Barth (The Christian Life, p.79):
Spiritual life begins at the very point where spiritual skill ends.
So much else that could be quoted, though. Read the whole post: it’s a real treasure-chest.