… no one shows you how. You don't sit up straight because whenever someone told you to, your back soon became tired and you slumped again. The reason your back felt tired is that you tried to sit up. The secret is in not trying. No effort.
Let your mind be as a floating cloud.
Let your stillness be as a wooded glen.
And sit up straight. You'll never meet the
Buddha with such rounded shoulders.
Bader DM. Zen Judaism: For You, A Little Enlightenment. 1st edition. New York: Harmony; 2002.
Why even bother sitting up straight? What's the harm in slouching? Several musculoskeletal problems can result, but none are as bad as the horrible consequences of cigarette smoking. I say this because chiropractic propaganda about subluxations often makes it sound like people with minor spinal misalignments - all of us, actually - have the Grim Reaper breathing his icy breath on our necks. So, relatively speaking, bad posture isn't so bad. You won’t die from the kind of headache you can get from slumping; neck pain is a real pain but people get used to it; and a herniated disc in the low back might or might not put you in the hospital. Nonetheless, it's a good bet that people with fewer such problems are likely to have more fun in life.
As I alluded to, the key to sitting up straight is that it requires no effort. The way to achieve effortless posture is through balance. This is explained in the following three figures.
The posture demonstrated in Figure 3 is close to ideal. Here the head is balanced over the spine and the natural forward curves in the neck and low back are preserved, as is the normal backward curve in the mid back. The position may look uncomfortable, but the key here is balance. Once the posture is adopted, you can relax in this position. No effort is required, but it takes a bit of experimentation to get it right.
A simple modification is to extend one leg forward so the foot is flat on the floor. This provides a modicum of additional stability and allows for further relaxation without compromising the posture.
THE MODIFIED COUCH SLOUCH. I often find myself sitting like this when I watch a movie, but I know it's not good for me. Most couches aren't conducive to sitting up straight. However, it helps to place a pillow behind the low back to preserve the natural arch and another one higher on the back to keep the head from moving forward in front of the shoulders. Strive to be a couch carrot rather than a couch potato.