Some of the niftiest are "neurobics" -- a term popularized by the late neurobiologist Lawrence Katz for engaging different parts of the brain to do familiar tasks. Try brushing your teeth or dialing the phone with your non-dominant hand. Theoretically, that can strengthen the pathways in the opposite side of your brain.
Since much of the brain is devoted to processing sensory input, Dr. Katz also suggested involving more of your senses in everyday activities -- such as showering or eating dinner with your eyes closed. "The brain loves novelty," says Dr. Doraiswamy. "It doesn't have to be complicated."