The best way I can describe it is, You know exactly what you want to say. But then there's this entity that you just always know is there, and you can just tell when he's going to grab your vocal cords and not let go. So you're then left with two decisions: You can continue to speak anyway, and the entity will grab this vocal cords and block of your airway and you're done for, you just have to stick it out until he says you're done. Or, you can choose to say something different, or just nothing at all. This all assumes you don't have a currently effective fluency technique of course, but at it's core I think this is a pretty good explanation.