Reading through the Psalms this year, it has stirred me to notice how frequently they are punctuated by "Be merciful to me, O Lord!" or "Be gracious to me!" The redeemed heart knows that he cannot live if God does not exercise his saving work on his behalf. God's free favor, his face shining upon us, is life itself. This recognition cannot help but come out constantly in cries to God for grace.
Prayers to God for grace are evidence that we rest entirely on God's grace, for life with him is all of grace.