The health of different countries evolves in parallel with their economic development. Communicable diseases play a more prominent role in low-income countries compared with high-income countries, while non-communicable diseases (NCDs) have become dominant in developing and developed economies. This transition has been accompanied by public health efforts to prevent NCDs, resulting in improvements in total life expectancy at birth (TLE). It is recognized that health determinants are not confined to healthcare systems, but that social determinants play a key role in health inequalities. The rapid increase in life expectancy at birth has led to increasing numbers of older adults, where health inequalities are accentuated. The current UN Decade of Healthy Aging calls for a life-course approach to building intrinsic capacity, maintaining function, and avoiding dependency with age instead of avoiding mortality and morbidity. TLE in Hong Kong is one of the highest in the world as a result of public health preventive efforts and an essentially free hospital system. However, the increase in TLE has not been accompanied by the same magnitude of increase in health span, resulting in an increasing dependency burden. Geography, culture, dietary and smoking habits, physical activity, urban planning, and neighbourhood cohesion are some of the social determinants affecting TLE and also health inequalities. With population ageing, it would be appropriate to focus on the social determinants affecting health span to maintain functional independence rather than prolonging life. A whole-of-society response instead of relying solely on the adaptation of health and social care systems would be needed, together with more nuanced metrics to measure health span.