Custom Bar GUI?

I am trying to make a bar, like stamina, or hunger or something. But I cannot figure out how. Here's the script I have at the moment, and the layout is here.

while true do
    if script.Value.Value > 0 then
        wait(.1)
        script.Value.Value = script.Value.Value - 1
    else
        wait(.1)
        return
    end
end

script.Value.Changed:connect(function(change)
    script.Parent.Size = UDim2.new(0, script.Value.Value, 0, 25)
end)