We joke and call them “senior moments,” but it’s not funny when you can’t remember a word, a person’s name or where you put your keys. The solution? Go take a walk. When seniors regularly took brisk walks for one year, an amazing thing happened: The hippocampus, the section of the brain that is involved in memory, actually grew in size, according to researchers from the University of Pittsburgh and University of Illinois at Urbana-Champaign. Typically, the hippocampus shrinks as we age.