The first step would be to figure out what is perfect posture and get into that position.  Then you essentially memorize it and learn over time how to recognize when you’re out of position, and what steps you can take to correct it.  Eventually it becomes second nature but yes it can take a long time and more effort than you can realize.  Still it’s pretty much the only way to ensure that you’re not screwing up your back all day in between workouts, even if your form during workouts is good enough to be painfree then…