Standing correctly is not the easiest task to accomplish. Our perception of ourselves doesn’t help. Everyone thinks they lean forward. The truth is that everyone leans backwards though they think they are leaning forward. That is some strange business. Let’s say you believe me that this is the case. It would be good to understand why so here is my take. I think everyone leans backwards to avoid feeling that their head goes forward. They can’t keep their head back due to a lack of core musculature that won’t allow their head to sit on top of the spine.
When I put someone’s legs directly under their pelvis, and get their shoulders directly over their hips, the head tends to pour forward in space, lost in its own world. When people tuck under to stand in what they think it straight, the head moves into line with the pelvis but everything else gets thrown off. If you are standing in my correct way and engage the muscles of the abdomen and core you should feel the ability to line the head up more successfully with the rest of the body but even then this is not easy.
When you see people with the bad posture that I am talking about—pelvis tucked under, thighs thrust forward, upper back rounding backwards and the head at the top, even though the head is moving forward in space it sits relatively in line with the pelvis. But everything else is thrown off as a result.
This all comes down to an issue of skeletal alignment and core tone. You need a lot of balanced muscle to steady the head on top of a well aligned spine. If you lack this muscle the bones tend to fall into a posture that causes trouble with a great deal of overworked and incorrectly used muscles.
There is always a chicken and egg dilemma running around these issues. You have to build some new muscle but you also have to change your skeleton. You can’t do one without the other.