There are many concerns people have with Botox about the impact it has one one's facial expressions. It is often parodied in comedies as freezing the face, making it expressionless. When done properly, Botox will not change your facial expressions and will create a natural result so that nobody else can tell that you have had Botox done.
Of course, there are some patients who desire to have no motion on the forehead and desire an excess amount of Botox. If this is the case, then you can tell your provider as such as the more Botox that is administered, the less motion that your muscles will have.