Let’s give some love to the benefits of good posture.

It’s sexy and you carry yourself with more confidence.  You look like you feel good and an uplifted heart encourages others to do the same. You are less likely to have a repetitive motion injury. Thirdly, because it is the most functional way to hold your body, you burn more calories just moving around doing daily activity. Most importantly, it encourages a correct breathing pattern and better sleep.
Tadasana: Mountain pose (the Iyengar way)

Feet:

Hip width (means even with sit bones) and parallel to each other.   Spread all of your toes wide. Lift and lengthen the soles of your feet from the middle of the arch of your foot forward on the floor.    Lengthen your toes forward as you spread them apart.  Then lengthen each foot from the middle of the arch back through your heels.

The parts that touch the floor most will be: the mound of the big toe (head of first metatarsal),  the mound of the little toe (the head of fifth metatarsal), and the center of the heel (or the inner heel)

Legs:

Lift knee caps, rotate/ turn thigh bone internally from your hip (without loosing alignment of knees).  Sacrum and tail bone move forward in space.  This action will stretch the front of hips.

Torso:

Front lower ribs strong and close to body (not flaring out as you will feel when you do the action with your hips)

Shoulder blades:

They are a triangle shape with the tip pointing down.  Slide entire shoulder blade slides down back. Tip points (on bottom) forward as if trying to push heart forward while the inner edged spread apart and slightly down.

Arms and hands:

stretch towards the floor. Upper arms turned out , Palms face body

Ears, shoulders, hips, knees and ankles are in one line. Tip of head is pulled toward ceiling (not arching neck), while neck is soft, face is soft and eyes gaze forward.

Breathe… Feel beautiful!

Carry this into walking by being aware of the way your feet hit the ground.  Do they glide parallel to each other or does one flop out to the side a little? Be aware of the subtle alignment and you will feel great.