As I said earlier, they lost it when they were young. They must learn how to bring the ability back again because everyone can do this. We all do it when the physical is asleep. So you must learn to do it while you are sitting in a chair, awake, or lying on a bed. You must learn to allow the subconscious to take over, and not let the physical mind control you.
Some people have dreams of flying.
Usually when people dream of flying they are out of the body because this is the way you get around. If you ever wake up in the middle of the night or early in the morning with a jolt, this is the astral body returning to the physical. Usually your dreams are in the beginning of your sleep cycle at night, and those dreams are nothing more than an accumulation of your thoughts during the day. It might not make much sense at first, but later on down the road, it will all come together for you. At its essence it is a personal spiritual experience, but it is not religious.