For our earliest ancestors who hunted and gathered, movement meant survival. Our brains evolved to reward physical activity. Moving, thinking and feeling have always been inextricably linked.    Yet what happens when we stop moving? Today, on average, we spend around 70% of our lives sitting or lying completely still. Our sedentary lifestyle—desk jobs, long commutes and lots of screen time—is not only bad for our bodies. It can also result in anxiety, depression and a lower overall I.Q.   But there s good news.  Even the simplest movements can re-activate our bodies and open up a hotline to our minds, improving our overall well-being and longevity. And we don t have to spend countless hours in the gym. In fact, exercise as we understand it misses the point.    Veteran science journalist Caroline Williams explores the cutting-edge research behind brain health and physical activity, interviewing scientists from aroun