Reason #3 Using another language is work for the brain.
Yudhijt Bhattacharjee cites various studies of bilingualism that demonstrate advantages beyond the obvious practical benefits in our globalized world. He concludes that keeping two language systems constantly in mind “… forces the brain to resolve internal conflict, giving the mind a workout that strengthens its cognitive muscles.”
In The Secret Life of the Grown-Up Brain, Barbara Strauch writes, “… bilateral use of brain power [such as bilingualism] may be the key ingredient in the power and creativity of our middle-aged brains.”
When you operate in two languages, fresh little pathways will appear in your sluggish gray matter. These days we all live such an improbably long life. We must constantly stir up the little gray cells.