A useful example is smokers that are quitting. Some part of their brains that can do complicated predictions doesn't want its body to smoke. This part of their brain wants to avoid death, i.e., will avoid death if it can, and knows that choosing the possible outcome of smoking puts its body at high risk for death.

I'm not even sure if this exact part of the brain wants to avoid death; maybe it's more complicated, and we have to introduce a third agent for that specific value (note that some say death might be a good thing, although they try to avoid it at all costs if necessary. This shows that the reasoning part of the brain doesn't automatically try to avoid death).