Catechism of the Catholic Church
2735 In the first place, we ought to be astonished by this fact: when we praise God or give him thanks for his benefits in general, we are not particularly concerned whether or not our prayer is acceptable to him. On the other hand, we demand to see the results of our petitions. What is the image of God that motivates our prayer: an instrument to be used? or the Father of our Lord Jesus Christ?
2736 Are we convinced that "we do not know how to pray as we ought"? 23 Are we asking God for "what is good for us"? Our Father knows what we need before we ask him, 24 but he awaits our petition because the dignity of his children lies in their freedom. We must pray, then, with his Spirit of freedom, to be able truly to know what he wants. 25
2737 "You ask and do not receive, because you ask wrongly, to spend it on your passions." 26 If we ask with a divided heart, we are "adulterers"; 27 God cannot answer us, for he desires our well-being, our life. "Or do you suppose that it is in vain that the scripture says, 'He yearns jealously over the spirit which he has made to dwell in us?'" 28 That our God is "jealous" for us is the sign of how true his love is. If we enter into the desire of his Spirit, we shall be heard.
Do not be troubled if you do not immediately receive from God what you ask him; for he desires to do something even greater for you, while you cling to him in prayer. 29
God wills that our desire should be exercised in prayer, that we may be able to receive what he is prepared to give. 30
English Translation of the Cathechism of the Catholic Church for the United States of America © 1997, United States Catholic Conference, Inc.