We all have the capacity to grow a bigger, fatter, fluffier hippocampus. And so what I like to give people is this image of every single time you move your body, it's like giving your brain this wonderful bubble back of neurochemicals ... I need my bubble bath of noradrenaline and dopamine and serotonin and growth factors. And with regular bubble baths, what am I doing? I'm growing a big, fat, fluffy hippocampus.