Shift to sprint with animation help?

Im trying to make a script to make it so that when the player presses shift the fov changes, speed changes and it plays my animation until shift is unpressed heres my current script:

local UIS = game:GetService('UserInputService')

local Player = game.Players.LocalPlayer

local Character = Player.Character

UIS.InputBegan:connect(function(input) if input.KeyCode == Enum.KeyCode.LeftShift then

    Character.Humanoid.WalkSpeed = 35

    local Anim = Instance.new('Animation')

    Anim.AnimationId = 'rbxassetid://7605028984'

    PlayAnim = Character.Humanoid:LoadAnimation(Anim)

    PlayAnim:Play()

end

end)

UIS.InputEnded:connect(function(input)

if input.KeyCode == Enum.KeyCode.LeftShift then

    Character.Humanoid.WalkSpeed = 16

    PlayAnim:Stop()

end

end)