Just fina alone? Watch it or you will burn quite a bit of muscle if overdone. I believe that cardio is grossly overblown. Diet is much more important. Cardio is best done right after awakening in the morning (prior to breakfast) or late at night on an empty stomach. If done first thing in the mosrning, one 30-60 minute session is all you need (depending on your metabolism). Taking a 5-10 gram dose of l-glutamine prior to cardio is a good idea also.