If God already knows what we need before we ask him, why pray?
We pray not to inform God of what we want, as though he is ignorant of our desires and needs. No, we pray in order to “exercise our desires,” as St. Augustine put it, so we can be made ready to receive what God is wanting to give us.
The problem, then, isn’t in God’s generosity, for he is ready to pour out his presence and gifts in abundance). The problem is that our capacity to receive God’s gifts has been wizened through sin. Our desires have been misdirected toward created things, and thus shriveled down to the size of those created things. As C.S. Lewis said, “it would seem that our Lord finds our desires not too strong, but too weak.”
God is pouring himself out in exuberance, but our capacity to receive is limited because our desires are 1) pointed in the wrong direction, and, because of that, 2) weakened to the point that created things feel satisfying to us.
We don’t live as we ought because we don’t yet desire as we ought.
Here’s where prayer comes in, then. In prayer, at set times and seasons, whether we “feel like it” or not, we “exercise our desire,” turning it toward its proper Subject, and thus increasing our capacity to receive from God.
We fan this properly-directed desire into greater flame through prayer. We learn to want better and want bigger, so God can pour out his gifts with abundance, according to the measure of his generosity.