I am doing some light reading this week and came across Tim Gunn's book, A Guide To Quality, Taste, & Style, and found wonderful reminders regarding one's posture. Rather than keeping the shoulders back, he suggests keeping them down, creating more space for the neck.
Also, I love the idea of the "bistro position." Imagine yourself slipping between two bistro tables and tucking your bottom under and drawling the navel in. Of course this idea originated in France and first appeared in Your Carriage, Madam written by Janet Lane.
I am going to try to remember to implement these daily!