Progress is different for each person and depends upon one's consistency, discipline, karma, and the will of the Being.
Beliefs do not help one to astral project. Beliefs are concepts in the mind, and thinking is an obstacle to conscious astral projection.
Desire is ego, and since humanity typically possesses 97% conditioned consciousness or desire, it enters unconsciously in the astral dimension without any awareness.
Conscious will is different, which is empowered in different degrees with mantras, first verbal, then silent. When an initiate has obtained perfection, one does not rely on things as one once did while striving in the path to the Innermost.
Remembrance is a powerful support on the path to God (Glorious and Majestic). Indeed, it is the very foundation of this Sufi path. No one reaches God save by continual remembrance of Him. There are two kinds of remembrance: that of the tongue and that of the heart. The servant attains perpetual remembrance of the heart by making vocal remembrance. It is remembrance of the heart, however, that yields true effect. When a person makes remembrance with his tongue and his heart simultaneously, he attains perfection in his wayfaring. –Al-Qushayri, Al Risalah: Principles of Sufism