For gross or better days, I'm positioned with the jaws between elbow and shoulder high (usually nearer collar bone) as measured by a hanging arm. Desk top at 5 inches or so above navel. Chair has good seat cushion, short bench, straight/erect spine, feet flat on the deck, thighs nearly level (knees slightly higher than the hip joint), and head phones w/nasal cannula. Beverage handy.