1. Good posture can get you hired. Once you're inside the room, the first thing your future employer sees is your posture. Mind you, they may not consciously know what they're seeing. Like that fine aroma that rises out from a good bakery, a great posture is instantly pleasing. The better the posture, the more people feel instinctively like having you around - so much so, that your resume becomes a lot less insignificant. They will start to make work for you to do, just to have any reason to keep you around. As my own posture has improved, I observe the following unexpected effect:
I could be having a very bad day "inside my soul," and yet I observed people still looking to get in touch with me, smiling and seeking contact - on days when I was as far from wanting that as you can imagine. In fact, when you observe babies very carefully, you find that the power of good posture is the great power that every infant has. And when you recapture a balanced, flexible, and elegant line in your neck, which you did have once when you were quite young, then people will again go goo-goo over you.
2. Good posture also means good health. A good posture, by which I mean one that is both straight-up and relaxed, allows the blood to circulate easily, and with such easy circulation, the body is better able to fight disease and cleans itself of the toxic byproducts of cellular metabolism. Thus, a good posture is one of the two best guarantee of good health - the other being good nutrition. In fact, we could eat the best balanced breakfast imaginable, with fresh papaya and coconut juice for everyone, and yet it will be for nothing - if our posture is so bad that our blood circulation is chocked off, or confined to only the major arteries and veins. Without balance and ease, our body's highways become like the streets of Milan. And no offense to the Milanese, but they've got rotting garbage in their streets. A free and easy circulation of the blood is essential to good health: without it, what nutrients we eat cannot reach our cells, what waste our cells produce cannot be collected, and where viruses and bacteria invade, our white blood cells cannot easily reach.
If you think about it, we move on a continuum, with perfect balance on one end, and perfect muscle tension, on the other. The more balance we find, the less tension we need, in order to sustain any given position. If standing, the ankles must rest easily on the heels, the shins must balance well on the ankles, and so on up the line, so that ultimately the head can float easily on the neck. If seated, then a similar idea applies, only now the weight of the body is mostly balanced on the pelvis, while the legs can at most interfere by dragging us forward and out of the chair. You can test your balance easily, by just turning your head to one side. Do this as and try to get a look at yourself in the mirror. A person with bad posture will show some degree of tension in the sterno-clydo-mastoid group of muscles - that collection of "ropes" that tie down the front of the chest to the back of the head. Tension here means that you are using muscle tension to fix your head in an upright position, instead of using balance to allow a full weight transfer to the atlas, or top-most cervical vertebra. The more weight is transferred to the atlas, the less muscle tension is needed to stop the head from falling off to a side. And so it is very easy to tell how good your posture is, by just looking at how much muscle action it takes to keep your head in an upright position.