From Heaven's Vantage Point
One who prays must direct his eyes downward and his heart upward (Yevamot, 105b).
The students of Rabbeinu Yonah understood this directive as an instruction to banish all physical and worldly pleasures from their hearts and imagine that they were standing in the Heavens above.
One of the main functions of Jewish prayer and meditation is to draw down Divine flow and blessing into this world. By looking down toward the earth, one will be constantly reminded that the purpose of prayer is not to escape from the world, as in other religions, but rather, to help sustain it.
There is, however, a negative effect that can occur when one directs his attention to this world. His heart may be drawn towards its pleasures, as it is written: “And do not follow after your hearts and after your eyes, which lead you astray.” We are therefore also instructed to direct our hearts upward toward Heaven, for only when our hearts are firmly directed towards Heavenly matters ― namely, the pursuit of holiness ― are we protected from being led astray.
Once a person is duly detached from this physical world, with his heart firmly rooted above, he will not be subject to the temptations of the heart. Rather, his passion and interest will be purely for spiritual endeavors. He will then be like an angel standing in Heaven, looking down towards the physical world below. Like the angels, who are able to see through the false illusions of this world, he will be able to see the true essence of what he desires. He will then pray for the correct things, and his intentions will certainly be for the sake of Heaven.
When, however, a person looks down without first removing his heart's desires from worldly pleasures, his prayers and requests can be misguided. He will believe that all his requests are for Heaven's sake, but that belief will be false.
When one is in the midst of heartfelt prayer, his connection to G-d is stronger, and the inner voice that stems from the conscience is easier to hear. At such times, a person’s temptations are weakened. This can explain why a person is reluctant to pray for foolish things. He is embarrassed to face G-d and ask for what he knows will ultimately serve no good. One should take advantage of the clarity of mind experienced during prayer to ask G-d for what he truly needs in order to serve Him better, thereby fulfilling the purpose for which he was created.