GOOD POSTURE is the body’s natural upward response to the gravitational field. The Alexander Technique approaches this concern by teaching you how to stop interfering with this response.
It’s not effective to hold a picture in our mind of what shape “good posture” is, and then try to force the body to conform to it. That would be exhausting, and would only work “till the phone rings” or some other distraction. This is why telling ourselves, or others, to “stand up straight” doesn’t work”.
On a physical level, we are freeing up the “postural reflex muscles”. On a more wholistic level, we are restoring our relationship to the environment, which includes the floor we are standing on, the seat we are sitting on, and the gravitational field, and much more. This is our more natural state. Then easeful, upright posture (and full breathing ) just happens, because your body is free to accept the support of the supporting surfaces. Once you experience this in an Alexander Technique lesson, you’ll be less inclined to start pushing your body around.