Saving lives is serious; learning how can be fun. Cardiopulmonary resuscitation (CPR), is the act of pushing on a chest when the heart is not beating (or pumping). When the heart works properly, it circulates blood and oxygen throughout the body. When you're in cardiac arrest, it is not and our hands need to be the pump. Place your hands in the center of the chest, clasp them together, straighten your arms, lock your elbows, and push hard and fast, using your upper body.