The more wood you pile on a fire the more heat you get, and thus it is with God - the more you think on Him the more you are fired with love and fervor towards Him. He who loves the Lord is always mindful of Him, and remembrance of God begets prayer.
Now you become angry and fainthearted and grieved, thinking that the heavenly Father is slow in answering. But I tell you that this will also happen as you desire—it will definitely happen—but first it takes prayer with all your soul, and then you must wait. And when you have forgotten your request and have ceased asking for it, it will come to you as a reward for your patience and endurance. When you reach the verge of despair while praying and seeking, then the fulfillment of your request is near. Christ wants to heal some hidden passion within you, and this is why He delays in granting your request. If you obtain it sooner, when you demand it, your passion remains uncured within you. If you wait, you obtain your request and the cure of the passion. And then you rejoice exceedingly and give warm thanks to God Who arranges all things in wisdom and does everything for our benefit.