How to make a hunger, thirst, and energy script?

I was trying to make a hunger thirst and sleep/energy script for my character, but it wouldn't work. I was also trying to make so if there is a gui on the screen, it will pop above the gui. But i don't know how to do that, so if you know how please tell me.

My script:

while wait(math.random(13,17)) do script.Parent.HungerFrame.Hunger.Size = script.Parent.HungerFrame.Hunger.Size - UDim2.new(0,math.random(1,2),0,0) script.Parent.ThirstFrame.Thirst.Size = script.Parent.ThirstFrame.Thirst.Size - UDim2.new(0,math.random(1,2),0,0) script.Parent.RestFrame.Rest.Size = script.Parent.RestFrame.Rest.Size - UDim2.new(0,1,0,0) end

(I also had that script inside the gui, with the hunger frame and thirst frame and energy frame.)

Some reason it didn't work.