That’s a great question and one that has kept philosophers busy for hundreds of years. The view that you are suggesting has been notably argued by French philosopher, Rene Descartes. It is the so-called dualist view, meaning that there is a distinction between ‘you’ and ‘your brain’ – or your body more broadly. If you are assumed that the two are separate, then the question of what causes what is puzzling. Is your brain controlling your behaviour or are you controlling your brain? However, we mostly think about it differently these days. According to the modern view, your brain is an important part of what makes the self – some people say that it is the seat of the self. In this framework, asking if the brain or you causes behaviour does not make sense, because they are both the same.