Medicare is a big deal. Its spending in 2015 totaled $646 billion and made up 20% of our total national health spending. It can cover a lot of what would be your personal health spending in retirement, too. Under current Medicare rules, enrollees will pay nothing for annual wellness visits with Medicare-accepting doctors and nothing when they get certain screenings, such as mammograms, colonoscopies, diabetes screenings, and many more.There's much more to know about Medicare, and if you're in retirement or anywhere near it, you'd do well to learn more, so that you can get the most out of the program.