This brief YouTube video captures what physical and cognitive therapists wish all of their clients understood. To say that the experience of pain is in your brain is not the same as saying it's all in your head. The sensitization of your nervous system is a real thing and a significant component of persistent, chronic pain. Watch the video for an illustrated explanation.

For a Canadian resource have a look at these videos below.  They are a longer and more in depth presentation of the topic:
Overcome Pain and Live Well Again Part 1
Overcome Pain and Live Well Again Part 2
Overcome Pain and Live Well Again Part 3

The best book on this topic is Explain Pain by David Butler and Lorimer Moseley

Check it out here: