On and Off switch on a simple script

If my script is a while loop, I've been trying to think of a way to enter and exit the loop at the press of a hotkey, in this case F1 and F2. I have tried 3-4 different methods that I thought of but some just press 2 indefinitely, others don't do anything at all. I know that you can make an Exit function that will completely exit the script, but I want to be able to turn the script back on with just the press of an hotkey and I think if you exit the script you can no longer do that so that's why I'm trying to find a way with Exitloop instead.

This is the last thing I tried (doesn't do anything)

#include <Misc.au3>

Global $ON_OFF = 0

If _IsPressed("F1") Then $ON_OFF = 1 ; OFF

If _IsPressed("F2") Then
    Do
        While 1

            send("{2}")

            If $ON_OFF = 1 Then ExitLoop
        WEnd
    Until $ON_OFF = 1

        $ON_OFF = 0

EndIf

Thanks.