Picture yourself in a loving relationship.
You first separate yourself from the body; then you identify yourself with the mind, and then you function on the mental plane, with this fine body just as you do on this physical plane.
Through concentration, you rise above the body-consciousness; through meditation, you rise above mind; and finally through Samadhi, you realize your spiritual nature.
These are three important exercises of Antaranga sadhana in the achievements of Kaivalya, the final beautitude. You can, by mere willing alone, travel to any place you like with the astral body and there materialize by drawing the necessary elements either from Ahankara or the universal storehouse, the ocean of Tanmatras.
The process is very, very simple to occultists and Yogis who know the rationale, the detailed technique of the various operations.