Walking three or four times a week grew older adults' hippocampus by one percent and left their memory better a year later, which no pill has managed.

But in the walking group the group that was randomly assigned to walk three four times a week for 40 minutes compared to a stretching group who's still engaging in exercise but not cardiovascular exercise. The walking group their you know hippocamp is actually increased in volume by 1%. So you're changing the the brain, but you're also changing the behavior. Their memory was much better a year later.