How to make fillable boxes in pdf form mandatory?

Hi,
 
I am interested in how to make a pdf form that doesn't allow the user to skip certain fillable boxes. I've created the form in InDesign, have Acrobat 9 Pro, and use a Mac. Is there javascript I can use to do this?
 
The final forms are typically filled in, then printed, signed, and sent in via snail-mail. (and some of the users are leaving important boxes blank)
 
I'm fairly new to creating these types of forms--can anyone help me?
 
thanks very much!