We have been hearing it for the last thirty years. Do 30-60 minutes of low to moderate intensity 'cardio' activity 3 to 5 times each week in your fat burning range of 60-70 percent of maximum heart rate. If you still believe that doing this type of 'cardio' workout is the way to go when it comes to getting into great shape and melting away body fat it could be why you are not making the progress you would like to make.
Or, even worse, you think you are in great shape but you are really just 'skinny fat', like most cardio junkies which is described as having low lean body mass (muscle tissue) and a high body fat percentage. Being 'skinny fat' is usually a problem of someone who continually feels they need to restrict their food intake or people who do primarily 'cardio' activity and not strength training exercise.
This is exactly the opposite of being in 'good shape' which is a term for having the maximum amount of muscle tissue and the minimum amount of body fat on one's frame.
It can be very discouraging to learn how high actual body fat percentage is when you spend so many hours doing 'cardio' activity.