Exercise every day, and you're more likely to keep your mind sharp well into old age. Staying physically fit throughout your life is not only good for your body, but also it's the perfect prescription for your mind and memory.

Researchers from the V.A. Medical Center in San Francisco found that adults who were the most fit at the start of a six-year study maintained their mental sharpness over time and did better in tests of their mental function conducted years later than did their less physically fit peers.

"Physical activity appears to be good for the brain as well as the body," according to study author Dr. Deborah E. Barnes. "Older adults with higher levels of cardiorespiratory fitness experience a slower rate of cognitive decline over time."