Nine and Ten year old children who are physically fit have bigger hippocampi and better memories than those who are not physically fit, according to researchers from the University of Illinois.

Nature Nurture Debate: Born Lazy? Don't like going to the gym? Hate exercise? Now there's an excuse: new studies on mice have shown that the desire to exercise may be largely determined by genetic factors. This suggests that some people may find it easy to increase their activity levels to get healthy, while others will struggle.