In this chapter, we will take an in-depth look at the role of physical activity in cancer prevention and treatment. We will explore how an active lifestyle can reduce the risk of certain types of cancer and how exercise can influence cancer cells’ development, proliferation and survival. In addition, we will discuss the different types of exercise, such as aerobic exercise and resistance training, and their specific effects on cancer cells. We will also emphasize the supportive role of exercise in reducing side effects of cancer treatment, improving physical performance, and promoting a positive outlook on life in cancer patients. Furthermore, we will discuss the recommendations for physical activity in cancer survivors and the importance of moderate exercise for health and well-being. Finally, we will summarize the benefits of regular exercise for cancer prevention and treatment and present strategies to increase physical activity in everyday life.