Progress! I'm no longer riding half-assed.

"Everything she says is true."

You know how sometimes when you get over one hurdle, other things fall into place?

It happened. And I think I'm riding better.

And to bring on this epiphany, my trainer only had to repeat the key advice for 3-4 years, probably 5,689 times, in as many different ways:

• Turn him from your outside aids 
• Put your weight evenly into both stirrups 
• Make sure your seat bones are weighted evenly 
• Step into your outside stirrup 
• Keep your shoulders over your hips 
• Ride the outside

Chalk it up to feel. 
In the last few months I've been developing a better feel generally for when I am sitting straight versus crooked, esp. on circles and turns. Specifically, I am consciously putting outside seatbone down and in solid contact with the saddle.  This puts my weight solidly over the right knee/heel, making my outside leg drop and relax, and my outside aids are clearer. And it always helps when you keep your eyes up.

Turning left, I exaggerate sitting right, which means I'm better centered and not leaning. I imagine  stretchy elastic string pulling my right seatbone to the right side of my saddle, keeping my weight over and allowing me only post only so high before sucking my seatbone back into place. This way I tuck his shoulder in because my leg is a relaxed, passive barrier -- and I can bump him a bit if he leans. Riley "gets" my newfound outside seatbone, and he obediently keeps his shoulder tcked/aligned around circles. A little inside leg and he offers a true bend. Amazing!

Always leaning in

I'm told that it is natural to want to push off with your dominant leg as a rider. I'm right-handed so the temptation is to push myself right over to the other side of the saddle. What's odd is that turning right, I also lean in, so whatever direction I'm turning, the outside seatbone is hovering somewhere in the vicinity of the saddle but not where it needs to be.

All of these years, I've been riding off my inside seatbone -- literally half-assed.