Women who walk for at least one-and-a-half hours a week are less likely to have memory problems than those who walk for 40 minutes or less, according to one study. The reason? Exercise increases circulation to the brain and helps it lay down new neural pathways. DO THIS: Vary your workouts. The more you can do, the better. Trying different activities is another way of exercising your brain as well as your body – so go for a brisk walk one day, then later in the week have a swim.