So, guitar is tough. Because it's not that you can teach someone how to do a G-C chord transition. There's no theory or understanding that goes into it.

It's muscle memory, plain and simple. You just have to do it a lot, over and over. I've had music teachers essentially say "that part sucked, you need to spend more time practicing it". There's no trick to be told, there's no intellectualization that will help. Practice.