Two common misconceptions about sitting:
1. Sitting straight does not mean that you sit perpendicular to the chair, which often results in locking the hip at a right angle, so that, as you work on activities that are in front of you, you bend the spine, either at the waist, shoulders, and/or neck.
2. Tilting the pelvis back, so that you sit on the tail bone causes the upper back and shoulders to round.
3. Below are some activities to help you sit Forward and Up, so you entire torso comes toward your activity from the hip joint.
Activity 1: As you are getting used to sitting on your Sits Bones, notice where you most easily pivot when you are sitting. Experiment with looking behind you, allowing your entire body to pivot around a Forward and Up axis of rotation. Try both sides. When sitting on your Sits Bones, notice that your shoulders are naturally wide. (See below)
Activity 2: Now roll back on the pelvis, until you are sitting on the Tail Bone. Notice how the shoulders round, mirroring the shape of the lower back. Instead of straightening your shoulders, simply roll forward again, so that you are sitting on your Sits Bones, and notice how your shoulders naturally widen.
Activity 3: Sit at a table in the Forward and Up Position, balanced on your Sits Bones. Reach for something far across the table. You'll notice that your entire torso comes forward from the hip joint. Now pretend you are coming slightly forward to do an activity like eating. In the same way that you came forward for a long reach, try to come forward from the hip joint (with a relatively straight back), for this more subtle forward movement. Many people lock their hips and bend from the waist, shoulders, and/or neck for these subtle forward motions. (See below.)
Activity 4: Sitting At a Computer: Sit in the Forward and Up Position, angled slightly forward from the hip joint, towards your activity (the computer). Align your computer screen with your angle of vision. The upper arm is parallel to the side and the elbow is bent at a 45 degree or slightly wider angle, so that your hands land on a slightly lowered key tray. (See below.)