Most HVAC contractors know about it. They can tell you how to insulate the slab and how much tubing is required. I have a few friends with it in their own buildings and they swear by it. It's a nice even heat and is said to be cost effective.
The fact that your only in 7th grade means that means your body is still growing physically (athletically) which is a good thing. Here's what you can do physically:
1.Find a ab workout you will stick to. Crunches are great when done properly to build your abs. I would workout 3-4 times a week.