Exercise.

You've heard it before: Exercise is good for the body. Now, scientists have found that it's also good for the brain.

Researcher Jennifer Weuve and colleagues at the Harvard School of Public Health wanted to know just how physical activity affects brainpower. So they challenged both couch potatoes and more active people to a mental test. Result? When it came to memory and thinking ability, those who were most active over their lifetime finished first.

How does a workout stretch the brain? Robert Sweetgall, a fitness expert who has walked more than 112,654 kilometers (70,000 miles) in his lifetime, explains: "Exercise helps oxygenate (supply oxygen to) the brain. [The supply] makes it function better." That's because when you exercise, your heart beats faster, pumping more oxygen-filled blood to the body. Like all cells, the brain's neurons (nerve cells) rely on oxygen to keep your mind working.

Even walking 15 minutes a day will help you focus better in class, says Sweetgall. So walk on, and wise up!

Did You Know?

* Besides improving strength and brainpower, exercise has been shown to reduce depression, stress, and sleeping difficulties.

* The hippocampus--located in the middle of the brain--is the brain region responsible for memory and learning.

Resources

* For a great guide to staying fit, check out the Centers for Disease Control and Prevention's Body and Mind Web site: www.bam.gov/fit4life/index.htm

* Discover more reasons why exercise is good for the body at: http://kidshealth.org/kid/stay_healthy/fit/work_it_out.html