Prayer moves what we know from our heads to our hearts. It's our hedge against hypocrisy, the way by which we begin to ring true. Our perceptions of truth are always ahead of our condition. Prayer brings us more into conformity. It bridges the gap between what we know and what we are.
Prayer focuses and unites our fragmented hearts.
We have a thousand necessities. It's impossible for us to purify them and simplify them and integrate them into one. He wanted to love God with his whole heart, but he couldn't sustain the effort. Other interests and affections pulled him and divided him, so he asked God to guard his heart and unite its affections into one. Centering on God each morning should be done as though it had never been done before.