This question examines health knowledge points.
Item B, World Health Organization: Health is not only a state without disease and weakness, but also a good state of physical, psychological and social adaptation. Healthy exercise should be moderate, not just quantitative. To sum up, B is correct.
Items A, C and D are the four cornerstones of health: reasonable diet, moderate exercise, regular life and psychological balance. It is inconsistent with the stem of the question, so it is excluded.
So the correct answer is B.