(X) is 60 years old, is 30 pounds overweight, has high blood pressure, and has been diagnosed with Type II diabetes. If he begins to engage in an exercise program of 30 minutes of brisk walking each day and eliminates from his diet prepackaged foods that contain high fat and high sodium, he may experience a substantial drop in weight and blood pressure and his diabetes may be easier to manage.

(Y) is 49 years old, runs on a treadmill for one hour daily, does not smoke, and eats well-balanced meals. His weight is normal for his height, and he has no chronic conditions. An additional 30 minutes of brisk walking each day may have just a minor effect on Y's overall health because he is already practicing a healthy lifestyle.

In this example, the marginal change in health statusfor the same change in exerciseis greater for X than for Y. Explain why?