How do I make a sprint button (pressing shift to sprint)?

I am making a capture the flag game and I want to add a sprint button. I would also like it if I could have help making it so that you stop sprint after sprinting for x amount of time with a 1 second cool down.

Alright in workspace insert a script (not local)like this

function onPlayerEntered(player)
	repeat wait () until player.Character ~= nil
	local s = script.SprintScript:clone()
	s.Parent = player.Character
	s.Disabled = false
	player.CharacterAdded:connect(function (char)
		local s = script.SprintScript:clone()
		s.Parent = char
		s.Disabled = false		
	end)
end

game.Players.PlayerAdded:connect(onPlayerEntered)

Insert another script inside that one not the code but insert new script inside that one so the script becomes that scripts child and make sure its a local script

local mouse = game.Players.LocalPlayer:GetMouse()
local running = false

function getTool()	
	for _, kid in ipairs(script.Parent:GetChildren()) do
		if kid.className == "Tool" then return kid end
	end
	return nil
end


mouse.KeyDown:connect(function (key) -- Run function
	key = string.lower(key)
	if string.byte(key) == 48 then
		running = true
		local keyConnection = mouse.KeyUp:connect(function (key)
			if string.byte(key) == 48 then
				running = false
			end
		end)
		for i = 1,5 do
			game.Workspace.CurrentCamera.FieldOfView = (70+(i*2))
			wait()
		end
		game.Players.LocalPlayer.Character.Humanoid.WalkSpeed = 24
		repeat wait () until running == false
		keyConnection:disconnect()
		game.Players.LocalPlayer.Character.Humanoid.WalkSpeed = 16
		for i = 1,5 do
			game.Workspace.CurrentCamera.FieldOfView = (80-(i*2))--Changes field of view sprint
			wait()
		end
	end
end)

Put a local script into your starter character scripts and put this in:

local inputservice = game:GetService("UserInputService")

inputservice.InputBegan:Connect(function(input, plr)
	
	if input.UserInputType == Enum.UserInputType.Keyboard then
		if input.KeyCode == Enum.KeyCode.LeftShift then
			script.Parent:WaitForChild("Humanoid").WalkSpeed = 60
		end
	end
	
end)