Staying hydrated keeps your memory sharp, your mood stable and your motivation intact, says Rachael Moeller Gorman in the July/August 2011 issue of EatingWell Magazine. When you’re well-hydrated, you can think through a problem more easily. Researchers hypothesize that not having enough water could reduce oxygen flow to the brain or temporarily shrink neurons—or being thirsty could simply distract you. While your size and activity level affect your fluid requirements, daily water needs for adults range from about 13 cups for men to about 9 cups for women (pregnant women and nursing mothers need slightly more), accounting for an additional 2 1/2 cups of fluids from foods. Daily water needs for kids range by age: kids 1-3 years need 44 ounces a day, 4-8 years need about 57 ounces, boys 9-13 years need 81 ounces, girls 9-13 years need 71 ounces, boys 14-18 need 111 ounces and girls 14-18 need 77 ounces of fluid a day. In addition to offering water with meals, remember that about 20 percent of our fluid intake comes from food.