A large amount of research confirms that physical activity and physical fitness are associated with health benefits in individuals of all ages. Achieving a sufficient level of physical activity and physical fitness will further consequently contribute to better health-related biomarkers.

In contrast, if time is spent in sedentary behavior, negative health outcomes are realistic to expect. Therefore, understanding and developing strategies to promote physical activity behavior is now more important than in the past, because it is essential to improve fitness levels. These strategies should cover all generations, children and youth, adults, and the elderly equally, because negative outcomes are visible in individuals of all ages.

The aim of this Special Issue is to provide an opportunity to publish high-quality research relating to the monitoring and promotion of physical activity and physical fitness. We welcome novel intervention research in school, community-based, or sports settings to promote children’s levels of physical activity and physical fitness. In addition, papers investigating the effects of physical activity on physical fitness in all generations are also welcome, including correlational and survey studies examining these relationships.

Potential topics include but are not limited to the following:

• Continuous monitoring systems of children’s and youth, adults or elderly physical activity
• Community-based programs for the promotion of physical activity in children, adults or the elderly
• Promotion of child and youth, adult, and elderly physical activity in primary health care
• Promotion of physical activity through active commuting
• Assessment of physical fitness as a health indicator
• Limitations and practical implications of physical fitness assessment in school and community-based context
• Heath-related outcomes of children’s and youth, adults, and elderly physical fitness