Qast means confidence, determination, choosing, and advancing straight toward a destination, thinking and reasoning moderately and deliberately, and living a moderate and balanced life. For Sufis, this term represents an initiate's pursuit of love and the pleasure of God, the Truly Beloved One, and the intent to realize this goal:
The heart is the home of God, clean it of others than Him,
So that the All-Merciful may descend into His home at night.
The couplet above, recorded by Ibrahim Haqqi of Erzurum in his Ma'rifetname (Book of Knowledge), expresses the intention of obtaining true love and His pleasure, and tells how to realize it. It concisely describes the way between decision and resolution and from resolution to destination. The only way to obtain peace of mind and be at rest without going to extremes and being exposed to spiritual trouble and pain is to seek the love and pleasure of God, and then order one's life around this aim. Rumi says:
A heart devoid of the Friend and seeking Him cannot be freed from trouble and pain. [As for] a head in which there is no love of the Friend, do not attempt to find any meaning and value in it, for it consists of bones and skin.
Those who have set their hearts on Him and have decided to reach Him never neglect to follow a way toward Him and to meet the necessities of traveling on it.  Even if they turn their eyes from Him for a single moment to look to others, they sigh for a whole lifetime. How unfortunate is the one who lives unaware of a way leading to Him. What a great loss, impossible to compensate, it is to fall and get stuck on the way after taking it.
Decision first appears and develops in the heart, grows firmer and stronger as a feeling, and then becomes a very powerful drive directing one toward his or her destination. In this context, decision signifies an intention and resembles a seed sown in the heart's soil. If the one who has this intention or seed in his or her heart receives help from God Almighty, the seed germinates and grows into an elaborate, fruitful tree. After a few steps traveled in decision, one finds resolution, which is defined as being determined to do something, steadfast in one's pursuit, and consciously fulfilling all responsibilities undertaken. Resolution is the first step toward the "heavens" of reliance and surrender. The Qur'an describes this step and the final point to be reached: When you are resolved, rely on (or put your trust in) God (3:159). If this first step can be taken through reliance on and submission to God, then the road becomes level and easy to walk on, and one travels it as if flying through the air.
Decision and resolution are two important dimensions or functions of willpower. Every traveler who intends to make a long journey must stop at the station of decision and resolution to receive the permit or visa, given by God, in order to progress to higher stations. Only after this does the journey truly begin. One who has taken the wings of decision and resolution feels attracted toward the goal and, no longer advancing by his or her own power, is taken to it. A friend of God says: Whoever overflows with the desire to meet with God, despite his inability to fulfill the requirements of the way leading to his goal, God Himself comes to him. God then becomes his or her eyes with which to see, ears with which to hear, and tongue with which to speak.
For the traveler who flies along on the wings of decision and resolution, meeting with God means finding subsistence in or through annihilation. For those with whom God wills and desires to meet, it means subsistence within subsistence,  and they suffer no trouble or pain in the "virtuous circle,"  where they encounter good after good. In this circle pain changes into pleasure, and wrath or chastisement are manifested as favors. One who has reached this point always utters in pleasure: Whatever comes from You, whether it be a favor or punishment, is good. With a cup of resignation in one's hand, he or she sips whatever comes from God, the Truth, as if it were the water of Paradise.