Many of us live in fear of mental decline in our older years, but now there may be something you can do to help! What happens to our minds as we age isn't just a matter of genetics or bad luck. Exercise — or the lack thereof — also plays a key role, according to two new studies in the Journal of the American Medical Association.

In one study, researchers followed more than 2,200 people aged 71 to 93 for seven years. They found that those who walked less than one-quarter mile a day had twice the risk of dementia than did those who walked at least two miles a day.

In the second study, researchers tracked more than 19,000 women for nine years and found that those who exercised the most cut their risk of memory problems by 20 percent. Those who walked at least an hour and a half a week also scored significantly higher on memory, attention, and other mental acuity tests than women who walked less than 40 minutes a week. So get walking! Every step will not only be good for your body, it'll also be sharpening your mind!