Q: How do you get a horse 'on the bit'?
A: Posture is a result of the movement, balance, and mental state of the horse. When they are in the best combination of the above, their posture will become the 'round' posture we are looking for.
Posture is less about a shape and more about a movement dynamic. As riders, we seek to be able to connect with this posture and not disturb it. When I am riding, if I feel an 'issue' with the reins or posture, my mind goes first to the body, legs, and mind. Horses need to respect the length of the reins, yet feel welcome to connect with them.