The concept of fitness has, more recently, started to revolve around the strength of your core which includes all muscles between your shoulders and hips. A strong core is the foundation of your overall health and will help prevent injuries, whether you participate regularly in sports or not. Planks: Start out with toes, body and forearms on the ground. Your feet should be about shoulder width apart. Raise yourself up by contracting your core abdominal muscles and make sure t