People who have higher cardiorespiratory fitness have fewer cardiovascular risk factors than people who are less fit, even if the less fit are equally or more active. This means you should improve your cardio (aerobic) fitness by challenging yourself instead of always doing the same workout. Move up a level on your bike or stair stepper, or try interval training: work hard for 2 or 3 minutes, then recover slowly for the same time. On the track, run a lap briskly followed by a slow lap. Do 4-8 intervals after a warmup once or twice a week instead of your regular workout, as a change of pace.