Feel the Burn

Let's be honest, most of us only perform cardiovascular activities to burn fat.  Yeah, yeah, it's good for your heart and lungs, but many of us who take the time to do cardio are more interested in the aesthetic benefits.  I'm not saying there aren't people out there who only care about the health benefits, but they are fewer and farther between.  Cardio seems like such a simple thing to add to your fitness routine--you basically just hop on a machine and go for it, right?  Well, not exactly, there are some basic techniques you can use to maximize the effectiveness of cardio; here are the ones I try to keep in mind at 6 a.m.  Note:  These tips are best suited for "leg-based" cardio--ellipticals, walking, stationary cycling, etc.