The Bible Dictionary entry for "prayer" says that "[p]rayer is the act by which the will of the Father and the will of the child are brought into correspondence with each other" and that "[t]he object of prayer is not to change the will of God, but to secure for ourselves and for others blessings that God is already willing to grant, but that are made conditional on our asking for them." How do we know what blessings "God is already willing to grant, but that are made conditional on our asking for them"?
As we study the scriptures, invite the Holy Ghost to be with us, and heed the feelings and thoughts we have, I believe we can know the right questions to ask; the Spirit can enlighten us as to what the Lord's will is for us generally and in particular situations, and then prompt us to know for what we should ask.
We also need to have faith and believe that God "is a rewarder of them that diligently seek him" (Hebrews 11:6).
This last part (faith in God's willingness to bless me) is something I am new to believing, and therefore I still have moments when I pray and wonder if anything will happen. I have the intellectual knowledge gained by seeing the Lord work in others' lives, especially in the scriptures, but I have yet to build up enough "heart knowledge" to match what I know in my head. At times this lack of trust has led me to pray for only the minimum of what I needed because I wasn't even sure the Lord would be willing to grant that, so why bother asking for more?
Stephen H. Peterson, a church service missionary serving at BYU-Hawaii, presented a devotional that addressed the topic of praying for the desires of our hearts--to not just pray for the minimum, but to pray for what we most desire and then expect the Lord to help us. He shared several examples from his own life, particularly in his professional life, where he prayed for what he desired and the Lord actually prepared the way for Brother Peterson to receive an even greater blessing than the one originally prayed for.
Hearing of Brother Peterson's experiences was very instructive to me. Since then, I have devoted time to examining my life and how the Lord has done that for me; with new eyes, I have noted many examples of that in my life, e.g. the new employment opportunity I have which is far and away greater than what I ever prayed for.
Brother Peterson summarized his thoughts on praying for the desires of our hearts by saying:
In one of Sheri Dew’s talks to the missionaries on Temple Square in Salt Lake City she taught a great principle. When you pray, ask for what you want or something better. I remember my grandmother saying aim high, you can always land in the gutter. The Lord knows your needs better than you and as a loving Father he will meet them or give you something better.In the scriptures, the Lord tells us how willing He is to bless us with what we desire.
Elder Stephen H. Peterson, “Desires of the Heart,” BYU-Hawaii Devotional, 28 April 2009 (emphasis added).
The "take away" from these scriptures and the devotional given by Brother Peterson is this: God is willing to bless us with more than we think He will--we just need to ask!
Ask, and it shall be given you; seek, and ye shall find; knock, and it shall be opened unto you:
For every one that asketh receiveth; and he that seeketh findeth; and to him that knocketh it shall be opened.
Or what man is there of you, whom if his son ask bread, will he give him a stone?
Or if he ask a fish, will he give him a serpent?
If ye then, being evil, know how to give good gifts unto your children, how much more shall your Father which is in heaven give good things to them that ask him?