Open, Relaxed Shoulders

Your shoulders should be relaxed and rolled back, making your chest feel open.

To understand what this means, think about doing a shoulder roll. This is a movement you have probably done many times, particularly if your shoulders were sore. Lift your shoulders up, pull them back, and let them settle down. When they settle into a resting position, your chest should feel wide and open.

Sitting in this way this may seem strange at first, because your shoulders may want to naturally round forward. However, if the muscles of the chest are sufficiently relaxed, the shoulders should remain open without difficulty.

Keep the Chest Relaxed

The important thing to understand here is that the shoulders can open without allowing the chest to rise. This is one of the most common sources of confusion for beginning practitioners. In order to bring the shoulders back, the practitioner will unconsciously lift the chest up, which increases the arch in the lower back. While this does have the effect of rotating the shoulders back, and does produce the appearance of good posture, it has a tendency to fatigue the muscles of the middle back.

Stretching

It is difficult to open the shoulders if the chest muscles are tight. For this reason, I highly recommend doing the doorway stretch or the strap stretch (see exercises) every day until the chest becomes more open. Thereafter, continue doing the strap stretch regularly to keep the chest and shoulders flexible.

Troubleshooting

Some people may have trouble keeping their shoulders completely open while siting with their hands in their lap. That's okay. As with the chest, the shoulders should pretty much take care of themselves, as long as the pelvis and hands are well positioned.

Do not actively pull the shoulders down. Just let them rest in a natural position. Also do not actively hold the shoulders back. This will create unnecessary muscle tension between your shoulder blades.