On the whole, we imagine acting to be a fun job, in spite of the fact that it can require a lot of time and dedication on the part of the actors themselves. However, some performers are so dedicated to their jobs that the roles they take can end up having some pretty serious effects on their minds and bodies. Daniel Day-Lewis is a prime example of a man who goes the extra mile - at a risk to his own mental and physical health - with every role he takes. He broke two ribs portraying a man with a hunch for My Left Foot and lived in the wilderness to prepare for The Last of the Mohicans, for example, but we could fill a video like this with his roles, so let's just give him the mention he deserves before we move onto the list itself. So, whether it's due to their preparation for their roles, or because of the things they had to do during the filming of certain scenes, here are ten roles that drove actors to the brink of madness.