You mean the activity designed for thousands of years to increase flexibility by slow and intentional movements helps your flexibility?
Crazy...
But if it's a back or lower body issue, walking a mile multiple times a week is likely to do more harm than good.
Like, if the cause of chronic pain is lack of basic physical activity, and can be cured by doing a very small amount...
Then that person never really had chronic pain. They just felt shitty because they weren't getting any exercise.
That's why the bare minimum of exercise showed a significant improvement