Persistent or Chronic Pain is pain that has gone on for (on average) more than 12 weeks.  It is a really common problem, often in the low back, but in other areas of the body too.  What we know from neuroscience research is that Persistent Pain changes the brain.  My University dissertation was on this subject in the context of Low Back Pain which can often become persistent.  There is a load of literature and research out there but here is a short and simple video that explains the issue nice and clearly.  Many of my patients have found this to be a useful introduction to the sticky problem of Persistent Pain.  The good thing is that many healthcare professionals are finding out more about this area.  If you would like to understand your own pain in this context I often explore it in Osteopathic consultation.