Walking and Running animations?

I have made walking and running animations that have distinct differences, and I want it to where if you have a WalkSpeed of 12-15, use the walk animation, and 15-25 would be running.

I was able to get this kind of working, but the problem is that if I switch from walking to running or running to walking it continues the previous animation. How could I fix this?

Sorry, I forgot to give my code.

local UIS = game:GetService("UserInputService")
local running = false
local WalkAnim = "rbxassetid://1580957360"
local RunAnim = "rbxassetid://1580965752"

game.Players.LocalPlayer.Character.Animate.walk.WalkAnim.AnimationId = WalkAnim
game.Players.LocalPlayer.Character.Animate.run.RunAnim.AnimationId = WalkAnim

UIS.InputBegan:connect(function(key)
	if key.KeyCode == Enum.KeyCode.LeftShift then
		running = true
		game.Players.LocalPlayer.Character.Animate.walk.WalkAnim.AnimationId = RunAnim
		game.Players.LocalPlayer.Character.Animate.run.RunAnim.AnimationId = RunAnim

		local keyConnection = UIS.InputEnded:connect(function (key)
			if key.KeyCode == Enum.KeyCode.LeftShift then
				running = false
			end
		end)
		for i = 1,5 do
			wait()
		end
		game.Players.LocalPlayer.Character.Humanoid.WalkSpeed = 24
		
		repeat wait () until running == false
		keyConnection:disconnect()
		game.Players.LocalPlayer.Character.Animate.walk.WalkAnim.AnimationId = WalkAnim
		game.Players.LocalPlayer.Character.Animate.run.RunAnim.AnimationId = WalkAnim
		game.Players.LocalPlayer.Character.Humanoid.WalkSpeed = 12

		for i = 1,5 do
			wait()
		end
	end
end)