Researchers conducted fitness tests on 2,747 20-somethings, making them run on a treadmill until they couldn’t keep up. When the participants were between the ages of 43 and 55, they all took the fitness exam again, along with cognitive tests. Those who could run or walk for longer in the initial treadmill test did better on the memory tasks 25 years later. And those who kept their physical fitness up in the intervening decades also had higher cognitive scores. Work out for a better body now and a better brain later.