Fitness Blender

Hello,

So I have started the fitness blender workout for 8 weeks and the calorie burn range I never seem to fall into and I don't know why since I try my best to keep up with it, but I am always between 50-100 calories before the minimum values. Maybe its just me being picky with numbers and not being happy with the numbers. I just like having a good calorie burn when I workout and I just haven't been getting it. As well would it be okay if I did an hour at the gym on top of this as well or would that be too much.