You are one walk away from a better day. In a University of Illinois study, kids who walked for just 20 minutes paid better attention and scored higher on a school test afterward, compared with the same kids on a day they sat still. Twenty children aged 9 and 10 came into Charles Hillman's lab on two different days. On one visit they rested before taking some tests. On the other, they walked on a treadmill for 20 minutes at an easy pace, the kind where you can still chat, and then took the same tests. The results came out in the journal Neuroscience in 2009. After the walk, the kids made fewer mistakes on a focus test where you have to ignore distractions and pick out one thing. Sensors on their heads showed their brains putting more effort into paying attention, and they did better on a standard school test too. Zero training happened beforehand, so nobody had time to get fitter. With only 20 kids and one session each, the study can't say how long the boost lasts or whether adults get it too. A short, easy walk right before something that needs your focus costs nothing to try.