CCC § 27: The desire for God is written in the human heart, because man is created by God and for God; and God never ceases to draw man to himself. Only in God will he find the truth and happiness he never stops searching for: "The dignity of man rests above all on the fact that he is called to communion with God. This invitation to converse with God is addressed to man as soon as he comes into being. For if man exists it is because God has created him through love, and through love continues to hold him in existence. He cannot live fully according to truth unless he freely acknowledges that love and entrusts himself to his creator."I will never comprehend my existence fully, for it rests in the infinite (God!), and man is finite. But, this little passage gives me a much greater understanding of what I can know as a human. God created man for himself, out of love. He cannot gain anything from man that He cannot do himself, for God is all-powerful. I think folks like Sartre took a wrong turn when they talk about existence, and forget about human dignity, which sets us apart from all of creation. I can't create my own meaning, my own purpose. I can't 'create' anything in that sense, only 'make' from what is given to me, and my purpose is not one of those things that I can make. (OK I use the term create in the popular sense. But that is only because, as a finite person, my language is limited.)
The epiclesis from Eucharistic Prayer III (only one of the new Canons that I would keep...) is really beautiful in the new translation (the one that took effect last Advent), and this section of the CCC relates to it, in my view.
Speaking of the EP: Prayer is what acknowledges God, especially the prayers said together throughout the world, and with the angels and saints AKA the Holy Mass, and the prayers of the Church (the Divine Office). Pray! God will grant you graces and favors if you pray, and St Theresa of Avila said something to the effect of "You give God a great compliment for asking very large things of Him.'You are indeed Holy, O Lord, and all you have created rightly gives you praise, for through your Son our Lord Jesus Christ, by the power and working of the Holy Spirit, you give life to all things and make them holy, and you never cease to gather a people to yourself, so that from the rising of the sun to its setting a pure sacrifice may be offered to your name.
Oh, and Ratzinger's very awesome-but-dense work, The Spirit of the Liturgy, contains a passage on the same topic. Good stuff, and I encourage you to check it out in due time.