i am still trying to get a grasp on this subject on how to burn fat with cardio. ive been reading lately e.g. you want to keep your heart rate at or below 120, but when i do this i feel like im not doing any work at all, its just like a walk around the block the pace is normal to me; and this is suppose to burn fat.

its hard not to believe that if your not sweating then your not working out.

any insight on this is greatly appreciated.