Voicemail

I have a recurring problem that seems to happen every time I attempt to leave a voicemail for someone.  It doesn't matter if it is professional or personal...if it is a friend or a receptionist...if it is something simple or a very complex matter.
Every.single.time. I just go on and on and on...not matter what.  Even when I prepare what I am going to say in advance--even if I write myself a little script.

What the heck is wrong with me?  Why can't I master this very mundane life task?

As a just punishment for my weakness, our new voicemail system doesn't allow me to delete a phone message until the WHOLE message has been played.  So now I get to listen to people like me leave lengthy, repetitive, annoying messages and there is nothing I can do about it.