This chapter discusses the effects of aging on the body's systems. It contains the effects of biological aging on health in later life. The chapter describes the effects of physical decline on activities of daily living and instrumental activities of daily living. It also describes how technology can help older people cope with physical change. The chapter shows how improvements in the environment can support a good old age. It discusses the importance of self-care and lifestyle improvements in creation of a healthy old age. The chapter also discusses the validity of the compression of morbidity hypothesis. It argues that the models of successful aging and assess the pros and cons of each model. The chapter provides the controversy over anti-aging medicine. The researchers said that assistive technologies, though not a substitute for personal help, may reduce the need for personal assistance.