For those who have not been into working out/athletic their whole lives, what did you struggle with most when you first started with Cathe (or whatever you started with, for that matter)? I feel like my legs are pretty strong in general, but I am really lacking (I think) when it comes to my cardio endurance. I just did Body Fusion for the first time and the weights part was easy, but the cardio was really really hard. I only had my step on the ground, I didn't use any of the risers. Does the cardio get easier? Is there anything I can do to build my cardio up with out feeling like I'm absolutely killing my lungs lol? Or do I just need to grin and bare it until my level gets where it needs to be?