This paper reviews endeavors over the past decades to achieve seamless monitoring of various types of physiological information by a variety of high user-affinity approaches applicable to the daily life environment. Developments in academic research and commercialization from the early period are reviewed. The latest outcomes are briefly investigated and roughly categorized into three main models: miniature portable monitors for ambulatory application, functional fabric-based wearable monitors for better comfort, and unobtrusively deployed invisible monitors for optimum usability. Monitors for seamless monitoring of physiological information in the daily life environment differ from conventional devices that are hospital-centered and aimed at short-term use in clinics. Through scrutinizing the current systems and examining their various pros and cons, we identify existing common concerns, provide insight into problem determinants, and suggest research topics for further study. In the near future, we envision that the home will be transformed into an intelligent hub for lifelong healthcare through seamless monitoring of the human body in the daily life environment, which will foster the development of a new discipline “Metrology of Health” or “Healthology” based on a holistic view of health.