It is best to sit straight with your head held high. According to Amy Cuddy, a Professor of Psychology at Harvard University, sitting upright can have a biological effect on the body that helps improve self-confidence. In her study, Amy saw found that when sitting upright with the body occupying a larger space, cortisol and testosterone levels in the body rise, which leads to an increased sense of self-confidence. So, if you want to feel confident in a short time, place your shoulders back, lift your head, and sit or stand straight. Your body will do the rest of the work.
By training, I am a American Board Certified Pediatrician. But in my younger years I grew up with natural alternatives. As a mom I have tried to incorporate both for my kids and it has worked wonders. And finally, as I am studying natural & alternative medicines, I realize the beauty and wisdom of living closer to earth. Hence in my practice I integrate both...for acute ailments I follow American Academy of Pediatrics recommendation but for simple and/or chronic conditions I prefer natural alternatives.
In western training we were raised to think that "health is the absence of symptoms and problems". But eastern sensibilities has educated me that "Health is state that allows one to use the full capabilities of their body, mind and intellect. Therefore, healthy living is a balanced state of well being: physically, mentally, socially and spiritually." This implies that healing is not a "one-pill-fits-all", but a personalized experience.