This is a technic I learnt whilst learning Kung Fu.

Back strait, shoulders back, chest out, chin up.

It’s to do with entering the world with no fear like a Shaolin Warrior & yada yada. The point is it gives you confidence through the use of this ‘stance’ & actually has health benefits such as opening your airwaves (you really can feel yourself breath better), straitening your back, & I’m sure many others. If you are a guy that is already indorsed in the fitness side of things, especially cardio exercises such as running, chances are you already have it without you noticing. So, all in all, if you want this stance without effort, just get fit!!!

This may strain your lower back at the beginning, especially if you’ve been off the fitness side of things.

Recap:

-Back strait
-Shoulders back
-Chest out
-Chin up

this is good advice.

the posture you are talking about is also used in meditation because it aligns your spine and helps you breath deeper. an easy way to attain it is to pull yourself up from the middle of your head, either visualize it or literally pull a piece of hair upward until your body/head come into alignment.

The Definitive Book of Body Language is a good read.