Muscle tension, particularly in the shoulders, is another common problem. If you tensely draw up the shoulders during practice or performance, consciously loosen them. Roll the shoulders forward and back slowly.
If discomfort persists, leave the organ bench and back up against a wall. Position the back of the head, shoulders, and hips in contact with the wall. Now stretch upward as you try to place the back of the neck and as much of the spine and shoulders as possible in contact with the wall. Remain in this flattened position for about a minute. This may help reduce tension.
As you return to the console, remind yourself throughout your session to play with relaxed shoulders and good posture.