These days we have so many options for cardio.  If you go to the gym and you look in the cardio area you will see a variety of different machines that are designed to help us do cardio.  Sometimes, it can be a little daunting picking which machine to use... The treadmill, the stair stepper, the elliptical, the AMT, the bike, the pool.  When people ask me what form of cardio is the best to do, I always say whichever one you actually do! The most important part about cardio is just getting out there and doing it.