Whenever your body is in a vertical position, it has to maintain equilibrium. If any weight moves forward or backwards, the centre of gravity of your body is going to change, and you end up with a very unstable structure that is it going to be easy to topple over.
This is what is happening to old people, this is why they fall randomly in their houses and break bones. Because they have such bad posture, they are leaning forward so much that they have the tendency to fall forward on their face.
But before this will happen to you, your body is an incredibly resilient structure. So what is going to happen, other joints out of your body are going to change position in order to bring the weight at the centre directly over your heals.
For example if you have a reversed curve in the neck, your head is now in front of your shoulders, and the weight of your head is pressing down in front of your feet.
You are going to have the tendency to fall forward, so what your body does in order to prevent that, is to overarche the lower part of your back and tilt the pelvis forward.
Which brings your head directly over your heals, maintaining the stability of your body.
In time as your head and neck bend forward more and more, it becomes impossible for your body to overcompensate by overarching your lower back, so you are going to walk around with an unstable structure.
One mechanical compromised joint is going to change the alignment of all the joints in your body. Because the upper part of your body has to be balanced on the lower part of your body, you always start the rehabilitation process by finding and fixing the highest mechanical compromise.
And the highest joint in your body is the atlas vertebra, the first vertebra between your head and the rest of the vertebras. This is what 99.9% of people have problems with, and this is why the treatment is almost always the same. An extensive amount of chin to chest stretching.
Also this makes the pain symptoms of your body to be counterintuitive, you might have pain in your knee and the conventional wisdom is to stretch the muscles around the knee or have surgery.
But the knee is in pain because it is misaligned because it is overcompensating for your neck. So working on your knee directly won't give you any resolution with your symptoms.
Despise the fact that your neck probably never hurt you, it is the reason why your knee is giving you a pain signal.