Because the claim based on the theory of Wallston found when people believe anything will cause practical behaviours consistent with the belief that, and affect the health.
The claim of Theoretical Wallston found that when people believe anything. To cause the behaviors that are consistent with the faith. And the impact on health care.
Since the claim according to the theory of Wallston found that when people have faith in anything. The practice of behavior will cause corresponding to that faith. And affect the health care.