Learning a foreign language benefits your brain and therefore, in the long run, your health too. It has been ascertained by MRI comparison tests in USA, on two set of aged people – one speaking only his native language, and the second group, multilingual – that Alzheimer disease was, by far, more present in the first group. That’s because a small structure of the brain located in the frontal lobe, and called Broca’s Area, processes languages interactions; if it has being used intensively – as the case of polyglots – in case of Alzheimer appearance, it can partially compensate for those brain areas affected by the disease.
By the way, the best method to teach any foreign language is the one which utilizes the “emotive” approach, by which, the teacher discusses with the learner topics that are of great interest to him or her. For a better comprehension of this method you may read this Jessica Lahey article appeared recently on the New York Times.