I don't understand why i can't keep my head in the right position/posture

[Sebastianc2012]

Have kind of bad Forward head posture, everyone says the best way to fix it is to keep it in correct posture a lot, and it will help strengthen and weaken the correct corresponding muscles.


But my problem is i can't even pull my head back right, If i try to pull it back and up as far as possible, it hurts pretty bad, and also is still not even in the right position, i can't get it that far, unless my torso is at a backwards angle and my chest is significantly lifted, but thats not right either.

When pulled it up and back i look like I have no chin, or a double chin in some cases.

I just don't understand why, is the posture that bad that i cant even temporarily pull myself into correct posture?