When riding well, you are looking for a marching walk, not a sloppy stroll. I read somewhere about "energisches Abfussen", German for "hindleg leaving the ground energetically" (is there a better term?) which is exactly what happens when you are marching.
1. Walk like a supermodel and swing your hips
2. March like a soldier and activate your core muscles (the collected type, not the extended striding type; think of musical kur); can you feel how the toes, ankles, knees and back are working? It feels a bit like a stick bobbing up and down inside me but not much hip swing.
3. Walk like a supermodel but activate your core muscles at the same time. It feels to me like something slows something else down and it becomes awkward.
To refine my question: is a lot of swing in the hips of the horse and a lot of "lateral slope" in my seatbones (which usually makes me collapse in my waist) an indication for the horse not using his belly muscles? Classical riding always talks about the swinging back, not the swinging hips. Can somebody shed light on this because now I am totally confused.