Camera position locking/stops following humanoid?

Made a simple shift to sprint, wanting to make the players FOV change when they engage and disengage sprinting. Here's my code

--player
local player = game:GetService("Players").LocalPlayer
local char = player.Character or player.CharacterAdded:wait()
local human = char:WaitForChild("Humanoid")
--camera
local cam = game.Workspace.CurrentCamera
cam.CameraType = Enum.CameraType.Scriptable


human:GetPropertyChangedSignal("WalkSpeed"):connect(function()
    if human.WalkSpeed == 24 and cam.FieldOfView < 90 then
        while cam.FieldOfView < 90 do
            cam.FieldOfView = cam.FieldOfView + 2
            wait()
        end
    end
    if human.WalkSpeed == 16 and cam.FieldOfView > 70 then
        while cam.FieldOfView > 70 do
            cam.FieldOfView = cam.FieldOfView - 2
        end
    end
end)

it produces this result: https://gyazo.com/3cbaf487456cc44c2e2044d507fa7cc7

Any ideas of how to stop it not being connected to the player? Also, the script doesn't go through the second while loop, when the FOV is greater than 70, help would be appreciated.