Many people whose employment requires physical exertion do not choose to engage in regular physical exercise when they are not at work. Exercise is a topic that is often omitted from discussion between doctor and patient during a patient's visit. Physical conditions that eventually require medical or nursing-home care often first predispose a person to adopt a sedentary lifestyle. A regular program of moderate exercise tends to increase circulation, induce a feeling of well-being and energy, and decrease excess weight.
A 1991 calculation was made to determine what, if any, additional health-care costs beyond the ordinary are borne by society at large for people who live a sedentary life. The figure reached was a lifetime average of $1, 650. Thus people' s voluntary choice not to exercise places a significant burden on society.
Which one of the following, if true and not taken into account by the calculation, most seriously weakens the argument?