Depth of Field: Stanley Kubrick, Film, and the Uses of History 1st ed.
Wife Elaine LaLanne was part of the show to demonstrate the exercises, as well as the fact that doing them would not ruin their figures or musculature.
At the novel's conclusion, it is suggested that the evil hotel forces have possessed Jack's body and proceeded to destroy all that is left of his mind during a final showdown with Danny.
King also viewed the casting of Nicholson as a mistake, arguing it would result in a rapid realization among audiences that Jack would go insane, due to Nicholson's famous role as in 1975.