The ecological model categorizes these components into five major categories: Individual determinants include biological and demographic elements such as age, gender, and socioeconomic position, as well as psychological aspects such as a person's confidence in participating in physical exercise, motivation, and attitudes about physical activity. Environmental factors are all those aspects of the living context that either facilitate or hinder participation in physical activity. Policy factors are defined as changes that are made to the social environment, such as public health initiatives or legislation, that may affect participation in physical activity. Organizational factors refer to the characteristics of an organization that may influence its ability to provide services needed by members to maintain their health. These factors include the size, location, funding, policy, culture, and other attributes of an organization. Community factors include the physical environment and the social networks within which individuals live and play. These elements can impact whether someone decides to participate in physical activity and if they do, how much effort they are willing to put forth. Public policies are established at the federal, state, local, and organizational levels of government. They include laws, regulations, and funding directives that influence what resources are available to support physical activity programs and facilities. Within this framework, researchers have identified several additional factors that may also influence participation in physical activity.