• Exercise your mind by reading, playing challenging games, and following current affairs
• Exercise your body to help keep your heart and blood vessels healthy and increase blood flow to the brain
• Eat a healthy diet to provide your brain with plenty of fuel
• Get a good night's sleep to help you retain information
• Stay socially active and learn new hobbies to engage your imaginzation

Although it's part of advertisement, I think it's pretty good information for brain maintenance.