Physical education practitioners and programs have the opportunity and obligation to help children become physically educated, healthy, and active adults. This article discusses the battle against obesity in K-12 learners from an exercise physiology perspective and focuses on the fact that practitioners have all the tools they need to battle this problem effectively. The tools to develop effective teachers are in various physical education standards and in the health and exercise science foundations of teacher preparation programs. Teacher candidates who are prepared to teach their students about the science of exercise and a healthy lifestyle will be able to promote behavioral change in their students by educating them on "why" and "how" physical activity is important for and beneficial to their health.