They depend on my attitude and sense of well being. When I was a child it was like swimming but with less friction; I was buoyant (or maybe there was no gravity).
In high school when I first became insecure, I began to fall out of the sky.
From this time, flying became very unstable (swerving) and required a constant strain to resist the force of gravity -- and was accompanied by a constant fear of falling to my death.
More recently, as I am gaining confidence again, flying still requires concentration, but it is smooth and stable, and now most dreams are partly lucid and I know I will not be harmed even if I fall.
As for the mechanics, as a child I swam, as a teenager created an upward lifting force with my hands, and more recently I am pushing downward against something invisible (I almost feel like a quadcopter).
Interesting. I have semi vivid dreams often. Basically I'm able to recognize that I'm dreaming but shortly after taking control or if I try to change to much I wake up immediately.
I did not succeed in lucid dreaming until I tried astral projection (entering a lucid dream while awake). I didn't succeed at this, but the efforts led to many spontaneous lucid dreams.
In other words, by trying and failing at something harder, I effortlessly achieved what had eluded me for 9 years.
