Every single time you walk around your horse to change sides you're actually signaling to him that you are submissive to him. Instead, you should be able to change sides without having to move your feet. This might seem like a simple concept, but believe me, your horse notices every single change. Every single time you can get your horse to move his feet, you're gaining a little bit more respect.
I tell clients all the time about how important ground work is for their horse and their relationship with their horse. It isn't done much in the US but it is truly the foundation of everything. This is a very good article. 'Horses regularly trained with ground work are more relaxed when ridden'