Making a script that shrinks a frame on button hold, help?

speed = 0.01 --Change this to alter how long it takes for hunger to diminish. A higher number is SLOWER (it waits that time).

		while script.Parent.Size.X.Offset >= 0 do 

script.Parent.Size = script.Parent.Size - UDim2.new(0,2,0,0)
wait(speed)

end 
end)

--How can make the frame shrinking script above work with the button hold script below?

local uis = game:getservice('userinputservice')

uis.inputbegan:connect(function(input,event)
	if event then return end
	if input.keycode == enum.keycode.leftshift then
		down = true
		while down do
			--my frame shirnking code I want inside the loop, I don't know how to put the frame shrinking script  in here withot the buton press script not working, help please?
		end
	end
end)

uis.inputended:connect(function(input,event)
	if event then return end
	if input.keycode == enum.keycode.leftshift then
		down = false
	end
end)