Run animation

local player = game.Players.LocalPlayer
local userinput = game:GetService("UserInputService")
local keydown = false

local runanimation = Instance.new("Animation")
runanimation.AnimationId = "rbxassetid://youranimationidhere"
runanimation = player.Character.Humanoid:LoadAnimation(runanimation)


userinput.InputBegan:Connect(function(input)
	if input.KeyCode == Enum.KeyCode.LeftShift then
		keydown = true
		end
end)

userinput.InputEnded:Connect(function(input)
	if input.KeyCode == Enum.KeyCode.LeftShift then
		keydown = true
	end
end)

while true do
	wait(0.1)
	if keydown == true then
		runanimation:Play()
	else
		runanimation:Stop()
	end
end