Brad and Alex are spot on.

CNC comes down to two things...the ability to visualize what you want to make and then draw it -- followed by the ability to visualize how the machine should cut it efficiently and then create the toolpaths that spell that out. There's a little more, such as understanding tooling things like speeds and feeds, but those first two things are the crux of embracing CNC to make stuff. I happen to love both of those things and find them mentally stimulating. A lot of it has become second nature to me after two and a half years and my CNC is "just another tool in the shop" ... one that I more and more turn to first. Why? Because I actually enjoy it.