It used to be an apple a day. Now doctors say a regular daily walk is what it takes to make women healthier, stronger and even smarter.

A recent study published in the Journal of the American Medical Association indicates that boosting your cardiovascular health can improve mental cognition. A research team tested more than 18,000 women, ages 70 to 81, and found that those who exercised about six hours a week had a 20 percent lower risk of cognitive impairment.

The exercise needn't be long hours on the treadmill or lifting heavy weights. Women in the study who walked a mile three to four times a week had quicker memory, a better attention span and greater learning ability than those who walked less frequently.

How does walking make you smarter? Researchers report that physical activity not only strengthens the heart, it directly affects the brain, stimulating the production of chemicals called nerve growth factors, that increase brain cell growth and survival. So don't forget to put on your sneakers and get outside this spring. Not only is walking heart-smart, you'll be doing your brain a favor too.