In terms of adaptability, unlike inanimate objects, living organisms exist in a dynamic balance between "wear and tear" and "repair and recovery". We regarded 17-hydroxycorticosteroids (17-OHCS) as a compound related to tissue "wear and tear" (Hans Selye) and sought for a compound related to tissue "repair and recovery". This led us to the discovery of 17-ketosteroid sulfates (17-KS-S) in urine. Elderly persons, unlike young adults, show low levels in 17-KS-S and little diurnal changes. In an elderly person 17-KS-S can decrease on significant life events (e.g. a spouse's death) and remain at low levels for a long time. Elderly persons with frailty need to improve their lifestyle (meals, exercise, rest, sleep, etc.) qualitatively and quantitatively to adapt themselves to stress adequately. Increased 17-KS-S levels were to be related to improvement in lifestyle.