How would I make this Animation Local Script work?

I HAVE TRIED! OK?! I HAVE TRIED!! SHEESH!! It's pretty obvious, I want an animation script to run and loop when Q is pressed and when Q is released, it obviously stops.. can you help? I mean, I got the animation working! Like, when I press Q it runs and all but I want the walkspeed to increase to 24.. but I also want it so, when you press Q again, it stops and the walkspeed returns to 16.

-- But what if I want to stop this animation? I tried to put 

wait(2)

local player = game.Players.LocalPlayer
local Mouse = player:GetMouse()

Mouse.KeyDown:connect(function(key)
if key == "q" then
s = player.Character.Humanoid:LoadAnimation(game.StarterPack.LocalScript.Animation)
s:Play()
else
	if key == "q" then
		s = player.Character.Humanoid:LoadAnimation(game.StarterPack.Localscript.Animation)
		s:Stop()
	end
end
end)

-- But idk if this is right. Oh! And I want mu walkspeed to be 24 when I press Q and the animation activates. Can you please help?

Animations can be added to a place either through a script or by adding an Animation object to the Workspace.

An animation object can be added to the Workspace by selecting Insert Basic Object > Animation The only property that has to be set is the AnimationId

local animation = Instance.new("Animation")
animation.AnimationId = "http://www.roblox.com/Asset?ID=144884906"

Playing Animation in Player Character

A model to be animated must have several parts to work. Firstly, it must have a Humanoid in which to load the animation itself with the LoadAnimation function. Secondly, it must also have a part called HumanoidRootPart. When it creates the animation from a timeline, the Animation Editor expects this part to exist. By default, player characters have both of these parts so only the animation has to be loaded in that case.

Loading the animation into a Humanoid creates an AnimationTrack which can then be played:

local animTrack = Humanoid:LoadAnimation(animation)
animTrack:Play()

Player character animations should be played from a LocalScript.

An Example:

-- Import animation
local animation = Instance.new("Animation")
animation.AnimationId = "http://www.roblox.com/Asset?ID=144911345"
 
-- Local variables
local animTrack = nil
local canPlay = true
 
function playShockAnim(Source)
	if canPlay then
		local player = game.Players.LocalPlayer.Character
		canPlay = false
		animTrack = player.Humanoid:LoadAnimation(animation) -- Load animation into Humanoid
		animTrack.KeyframeReached:connect(function(keyframeName) -- Bind function to KeyframeReached event
			if keyframeName == "ElectrocuteEnd" then
				canPlay = true
			end
		end)	
		animTrack:Play() -- Start the animation
	end
end