In a good posture least strain are placed on the supporting muscles and ligaments. This article shows a technique to make a posture brace at home involving just a strap. This can be done on a experimental basis just to check how a good posture is supposed to feel.
Requirement : 2 to 3 meter strap (yoga strap or two men’s ties knotted together will also do, I am using a strap from karate uniform)
1. Place the strap over your upper back and hold the ends in each hand (as if you are measuring your chest)
2. Drape each end of the strap over its respective shoulder (do not cross the strap in front of your body)
3. Cross the strap in back holding one end in each hand.
4. Pull the straps slightly in such a way that you feel a little pull in your trapezius muscles in your upper back area near your neck. Your shoulder blades will also be pulled in slightly (they will come closer). Secure the ends at the front (you can tie a knot or fix a velcro)
Walk around the room while adjusting the strap slightly. Notice how different it feels to walk when you are aligned this way. You will feel lightness in your body and feet.
This is just a preview of how a good posture is meant to feel. (Rather than wearing a posture brace it is recommended to strengthen and stretch the muscles for a good posture)
When our body is aligned properly then the muscles have to do minimum work, this is the reason that your body feels so light.
You might also be interested in this article to correct your posture.