Is Your Desire Caused by Your Brain State?

Physicalists would like to have a view of mental causation. They want the mind to be able to do something, because they recognize that if your thoughts don't really direct your actions, they're no longer rational. There are people like jaguan kim waiting to say that it's hard to see how the a mental qualities, the mental properties of you could cause anything. He calls this the exclusion problem. Because everything about your states is really caused by the brain. Aren't those brain states also sufficient to cause the next state of your nervous system and also everything that your body does? And if they are, then there really, really isn't any room for your mind to do anything