In my experience pain and stress are a really bad cycle, and I could understand this a lot better after learning more about what stress actually is.
Experiencing physical pain sets off a stress response, and that means among other things: shallow breathing, heated thinking, worse digestion, higher blood pressure and worse circulation. And unfortunately several of these things directly intensify my physical pain, the worse circulation especially.
So stress and chronic pain turn into a negative cycle, they both feed each other.
How can we break this cycle?
Thankfully, there's one simple tool that is really close at hand: Our breathing!