Custom health bar not regenerating?

My custom health bar is working fine other then the fact that it keeps going down instead of regenerating back up.

game.StarterGui:SetCoreGuiEnabled(Enum.CoreGuiType.All, false)

local player = game.Players.LocalPlayer.Character
repeat wait() until player
local humanoid = player:WaitForChild("Humanoid")
local TheMathPart = humanoid.Health / (humanoid.MaxHealth)


function TheHealthbar()
	local TheMathPart = humanoid.Health / (humanoid.MaxHealth)
	script.Parent:TweenSize(UDim2.new(0, 25,TheMathPart, -180), "Out" ,"Sine", .5)
end

humanoid.HealthChanged:connect(TheHealthbar)

Help would be appreciated.

Y u be setting TheMathPart twice