” is to make whole. A person is said to be ailing when she / he is not whole; could be mentally or physically.
Have you ever thought yourself as ailing because you have only two hands? The great majority of people have also never done so. Yet when a person loses one of his hands, he or she could become completely incapacitated , often more in the mind than in the body. Many people who are differently abled, go about their lives without giving it a second thought. Many also become completely obsessed with the apparent lack.