I've been trying many methods, none of them work. I'm not asking for a script I am asking for a direction that works. Thank you.
EDIT:
I made a script, but it still doesn't seem to work.
local userinput = game:GetService("UserInputService")
local hum = game.Players.LocalPlayer.Character.Humanoid
userinput.InputBegan:connect(function(input)
if Enum.KeyCode.LeftShift then
hum.WalkSpeed = 60
else
hum.WalkSpeed = 16
end
end)

1 comment
http://wiki.roblox.com/index.php?title=API:Class/UserInputService/IsKeyDown