In Law School, early 1970s, I found my way into Yoga class. When I started working, I brought some of what I learned into the office, and into the Courtroom. I soon realized, "posture" in advocacy is assisted by good posture in your body. Yoga teaches posture, among other things.
The second thing we did in my 1970s yoga class was to sit erect, with some help from our breath.
(1) Sit straight, feet flat on the ground, and hands flat on your quads.
(2) Consciously align your heart over pelvis and your head over heart. Tuck the chin in a little.
(3) Close your eyes and focus between your eye brows, or focus on a point straight ahead and level to your eyes.
(4) Consciously inhale, bringing the breath into the bottom of your lungs (allow your belly to push out). Then fill the middle of your lungs (your rib cage will expand), fill the top of your lungs (your shoulders will lift slightly), and lastly, pause to notice how your breath made you taller (your spine taller).
Practice Note: If possible, do all exercises with your eyes closed and focused between the eyebrows. In between exercises, a breathing exercise, or a physical exercise, we always paused for 30 seconds. During this half minute or so, we consciously observed how our body and mind felt.
For both of these breathing exercises, start for 1 minute, work your way up to 3 minutes. Then do a 1 minute stretching movement. At home, build up to three minutes.