This is the latest question I've answered on the Quora platform, where people ask the general public about anything and everything:
What are some ways to fix poor posture and back pain without having to see a doctor or chiropractor?
Look into the Alexander Technique.
It can be tricky to learn from a book, although possible if you put the time in and have the self motivation. It's much easier to learn from an accredited teacher, but maybe start with a book, it may be enough, and will at least pique your curiosity and see if it's something you're drawn to.
It's aim is to prevent the habits and behaviours that cause poor posture in the first place. You don't need to do good posture, but prevent poor posture. Trying to do good posture usually results in unsustainable effort and is usually based on a misunderstanding that posture is a position, when in fact, it's a movement, a balancing act as you spontaneously refind the support that the ground is offering you. It's a dynamic and unstable equilibrium. It's the trade off for our exceptional mobility. It's about coordination rather than strength.
You no more need to do good posture than you need to do blinking or breathing. You will be blinked, you will be breathed, you will be poised. Poise has far more value than mere posture, it's a quality, not just a shape, a quality of mind and thinking in activity.
The advantage of the Alexander Technique is it empowers you instead of leaving you as a passive patient, it's a tool for growth and self learning, not just physically, but mentally as well, great for stress management. Poor posture is often a sign of habituated poor stress management.
With regards to back pain, a gold standard randomised study funded by the NHS in the UK, and performed by Southampton Universtity, showed clinically significant results which were published in the British Medical Journal, and is recommended by backcare.org.uk and Dentists Provident, the main health insurers for the dental profession in the UK.
You can read more about the Alexander Technique here ...