You can find the official digital edition (PDF and ePUB) of Overcoming Poor Posture: A Systematic Approach to Refining Your Posture for Health and Performance by Steven Low and Jarlo Ilano on the Steven Low website
Before you can fix the problem, you need to identify it. Most people fall into three categories:
If you're looking for more information on overcoming poor posture, here are some PDF resources that you may find helpful:
Excess screen time and looking down at your phone.