It is fairly well understood in the pain community that there is an association between catastrophising (essentially, dwelling on the worst case scenario) and pain related disability (Linton & Vlaeyen, 2012). The theory goes that worrying excessively about our pain or condition makes us less likely to attempt to do things that might make that pain any worse, and subsequently we avoid things. These means that over time we lose function and become less able to do the things that are important to us.

http://beyondmechanicalpain.com/pain-in-children-what-role-do-parents-play/