Thanks for the article on rumination. According to my understanding of neurons is, that when neuros fire it makes them healthy and more easy to fire in the future, so that when one forms a thought loop of negative ideas those neuron in those pathways are nice and healthy while the other neuron are getting weaker and weaker and so once one has a deeply ingrained neuron patterns it is hard to get other pathways (hard to teach an old dog new tricks scenario) established.
Training is required and maybe some type of chemical intervention could be helpful.
http://www.cbsnews.com/news/magic-mushroom-psychedelic-may-ease-depression-anxiety/
But this only deals with depression and not organic mental illness which I think is a major contributing factor, while not minimizing enviroment (cult indoctrination)(unhealthy thinking thought loops).