Health maintenance and prevention would do a great deal to reduce the costs of health care. It would reduce the amount of money that would be spent on expensive doctor visits and tests. It is for this reason that insurance companies (as well as organizations that employ and insure large numbers of people) want to promote health maintenance and prevention.
The opposite of prevention is when a person does whatever they want until they get sick or hurt, at which point they go to a doctor. Prevention seeks to keep people healthy in the first place. It promotes things like good eating habits and exercise. When people pursue such habits, they reduce the amount of money that has to be spent restoring their health because they are less likely to lose that health in the first place. Therefore, promoting health maintenance and prevention would reduce the costs of health care.