According to Osho, after deep and fast breathing the body feels extraordinarily light, as body-consciousness drops and oxygen rises, awakening kundalini. This produces a sense of bodilessness and weightlessness that the mind pictures as levitation; rarely does actual levitation occur. These are soul-level experiences, not bodily events, so don’t be alarmed—observe the lightness as a sign of inner awakening.
Strong breathing can make you feel floaty, like flying, because your mind turns real lightness into that picture—your body stays on the ground.