Endless cardio is stupid, compromises your lean muscle mass, causes motion injuries, is not the effective way to train, and is incredibly boring, unless you want to look like you live in a jungle and run between villages.
A better training method is HIIT which is 5 to 7 times more effective, per minute, than slow burn cardio.
HIIT has the added benefits of not compromising nearly as much lean muscle mass, taking far less time to execute, AND it increases cardiac threshold.
HIIT has been studied to death by many folks, and the old school hours and hours of cardio has been proven time and again to not be nearly as effective as HIIT. For me, HIIT melts fat off as long as I keep my calories up to support that intensity of activity.http://en.wikipedia.org/wiki/High-intensity_interval_training
8 to 20 minutes of HIIT (not counting stop times) daily will melt the fat off you in record time, and markedly increase your cardiac threshold without taking 120 days, and without ruining your skeletal muscle by using it as fuel.
Stairs, step ups, bleachers, burpies, lines, sprints, etc, are incredibly intense cardiac exercise that will have your metabolic jumping.
It's critical to keep calories up to sustain and promote high intensity activity.