Remember when people used to say that one day, Amazon may surpass Walmart in sales? At one time it seemed like a pipe dream, but the day has come that Amazon may overtake Walmart soon as the world's largest retailer. Walmart is not giving up the fight, however.  We'll review a Wall Street Journal report on what Walmart is doing to fend off Amazon, then Shelley Grandidge joins us joins us for a Q & A on health insurance and Medicare.  MASTERING MONEY is on the air!!!