Forward head posture and hyperkyphosis (rounded shoulders) "are associated with with poor health outcomes including neck pain(13), jaw pain(14), carpal tunnel syndrome(15), headache(16) and increased fall risk(17 18)..." Science Catches Up, Rajal Cohen, 2018
Many people also look and feel less confident and cheerful in this type of posture.
So how can you go about changing this habit?
Often people believe that they need to make more effort in order to correct this slouch. Phrases like 'pull yourself together' or 'hold yourself tall', 'push your shoulders back', 'develop more core strength', etc come to mind.
The truth is none of these strategies are effective because they all have something in common. They require effort and so are very hard to maintain over time. Increased effort is simply not the right answer.
Learn to balance well.
Your head is very heavy, approx 5kg (the same as a 5l bottle of water). How you go about managing this weight will affect your alignment for better or worse. If you habitually carry your head forward of your centre of gravity you are creating way more work for your whole structure than is necessary.
So should you just pull your head back in? Unfortunately it is not that simple. It will be unsustainable as it will require a lot of muscular effort to go against your habitual way of holding yourself.
What is more helpful is to learn to let go of the muscular tension that is pulling your structure out of its natural balanced poise. You may not be able to feel the tension that is pulling you out of shape. This is because it is always there as a habit and so it feels normal and therefore right.
A qualified Alexander Technique teacher can help you to identify and release the tension that you don't need by using very gentle manipulation and verbal guidance. You can learn the skill of releasing tension and find an easier way to live, with less strain and more confidence and grace.