Anecdotal but walking significantly helped me as well. I did a lot of PT for my back issues and while they were somewhat helpful the only thing that really made it go away for good was several miles of brisk walking every day.
At least for me it's certainly some muscle thing as once winter comes (and I'm walking less) the back problems come back. One of the best things this winter was getting a job in an large sprawling office, which means I'm walking several miles every day at work (all indoors). Haven't had any issues this winter at all.
"At least for me it's certainly some muscle thing..."
Again, I think a good mental model is that of a corset, or a brace. In this case, the corset you are donning is made of your own muscle.
You could attempt to build that own-muscle corset section by section by doing all of the 40 different trunk and midsection rehab exercises, but even then, in what balance or proportion could you hope to execute them ?
Instead, you can hit all of them, in concert, and in appropriate proportions, by walking.
The difficult part is that bad back pain will not make for easy, pain-free walking - at least at first. I found 4-6 mile walks to produce a fair amount of back pain in the year immediately following my initial disc herniation/tear. It took that forced week or so at the beginning of basic training to pull my spine back together.
At least for me it's certainly some muscle thing as once winter comes (and I'm walking less) the back problems come back. One of the best things this winter was getting a job in an large sprawling office, which means I'm walking several miles every day at work (all indoors). Haven't had any issues this winter at all.