Aerobic exercise isn't just beneficial to your heart, it also sharpens your mind.
What's more, moderate aerobic exercise will do the trick. Several studies involving older adults demonstrated that simply walking a mile or so three times a week increases blood flow in the brain and strengthens connections between neurons, resulting in improved mental performance on tasks requiring attention.
One of the studies divided a group of seniors into two different six-month exercise courses--one course consisting of aerobic exercise, the other consisting of stretching and toning. Again, we're not talking about marathon-training here.
The aerobic-training course gradually built its participants up to walking 45 minutes at a moderate pace three times a week. At the end of the course, the people who completed the aerobic training showed significant improvements in attention-related mental tasks. The stretching and toning group showed little improvement.
So strap on your walking shoes and get moving!
"Aerobic Exercise Training Increases Brain Volume in Aging Humans" (The Journals of Gerontology)