Duke moved like John had just ridden him

Duke started out today kind of flat and sluggish.  John asked me what was wrong, and I started to list things, and he stopped me and told me to start fixing them, one at a time.  So we started with getting Duke forward.  John had me get him WAY more stepping than I would ever dream of doing by myself, and from there, we started to make him bend and then get round.  He said the same thing happens to me at shows, I get overwhelmed and I don't break it down into steps.  Just pick the first thing, work on it, and then work on the next thing.  And hot damn, it worked like a charm.  After we got forward, we worked on bend (Duke was stiff in his jaw) so I moved bent his neck to the inside, then to the outside.  If he tried to fall in, I pushed him out with my inside leg, and then when he tried to bulge out, I used my outside aids to keep him on the circle.  From there, we went to 10 meter circles and then pushing him in and pushing him out, just to get him to bend his body.  On the 10 meter circle, when I got to the "middle", if I rode it like I was going to change direction (and then didn't) it helped me use my outside aid better on the first part of the next circle.
Then the magic happened, and of course it was magic so I can't really describe it.  The end result was that we had medium trot, and I could totally feel it, and then we had real honest to god lengthening and I could totally feel it.  But how we got there?  It had something to do with Duke stepping forward, and then bending, and then going round, and then I asked him to go forward with my legs but I used my hands with the round aids and so his step got bigger and bouncier instead of faster.
We worked on the canter too, with the same feels, and then John had me work on the sitting trot which was massively unpleasant.  Even though Duke was moving big and soft, I just couldn't unlock my back and I just pounded around up there on the poor guy.  For the sitting trot and for the canter, John had to tell me to sit up and to put my butt down in the saddle, I just kept tilting more and more forward.
At the end, he told me to halt and we halted - boom - perfectly square.
It was pretty amazing because I've never gotten Duke to move that well for that long by myself before, especially starting so dull (but John said with attentive ears) and so it was cool that I could do it, even if I needed John talking me through every step.  And I could totally feel the difference in the movement, and I could answer a bunch of John's questions about what was wrong and what the aid was to fix it; I just wasn't applying them but passively waiting for him to say it (I'm afraid I'm wrong).  It felt amazing, and I wish I could ride like that every day, although it was also kind of exhausting.