I tried to put the default animation script and alter it then later putting back in the tool. it hasn't worked so far.
script.Parent.Equipped:Connect(function()
script.Animate.Parent = game.Players.LocalPlayer.Character
game.Players.LocalPlayer.Character.Humanoid.WalkSpeed = 30
end)
script.Parent.Unequipped:Connect(function()
game.Players.LocalPlayer.Character.Animate.Parent = script
game.Players.LocalPlayer.Character.Humanoid.WalkSpeed = 16
end)
script.Parent.Activated:Connect(function()
end)

2 comments
It probably isn't the best idea to swap out two separate scripts whenever you need to change animations.
You should manually load the animations instead of this. Search animations on the wiki.