Cardio, or aerobic, exercise is pretty much any activity that results in more oxygen going through your bloodstream. Most popular sports are some type of cardio exercise as well. Our culture has a mistaken assumption that somehow cardio exercises are more beneficial for younger people. Something for the more flexible and lithe to engage in. The truth is that as we grow older, aerobic exercises (as well as core and strength training) become even more important for keeping us active, able to get around easily and with a healthy brain.