Dojo rat sorta mentioned in his comment one of the next things I wanted to talk about - How do societal aesthetic values affect our perception of 'good' posture or motion? For instance, check out this picture of Usher-san that I labeled "Great posture." Usher has a mesomorphic (stratight, athletic) body type, which is generally more aesthetically accpetable than an endomorphic (softer, rounder) body type. Even if I were to take a photo in that same position, someone comparing the two pictures would likely say that Usher's posture is better than mine. Body shape plays into subjective evaluation of posture.
However, a pretty-much infinite amount of research has shown that most people's perceptions are skewed when it comes to their own bodies. I remember graduating high school weighing between 169 and 175 at my current height of 6'1". I've seen pictures taken during that era in which I look rail thin - almost gaunt. Years later, finishing graduate school, I weighed about 210. And looking back at the pictures, you can still see all the angles in my skull. I still looked skeletal - even with an extra 40 pounds. Now I'm a good bit heavier than that (though still a good bit lighter than my lifetime peak weight). Here's the kicker... I have always felt fat. Even when I knew that I was at about 3% bodyfat in highschool. Even knowing that body perception is so skewed that eating disorders prevail in the population.
So, where am I going with this? If you are going to evaluate your own posture and call it 'good' or 'bad' posture, then you need some criteria outside of how you feel about it because how you feel changes with the temperature and humidity and how your friends are treating you and every other variable in the world. I have found that brainiacs like Feldenkrais and Alexander and Hanna and Laban have given us some pretty good guidelines and criteria for evaluating motion and posture. See the list of Feldenkrais principles in the previous post.
Over the next several posts, I plan to work through these men's ideas about posture and post a series of thoughts about how they relate to my body and to aikido and judo in particular. Stay tuned, faithful reader...