Sprint Script | Roblox Studio

local userInputService = game:GetService("UserInputService")
local userName = script.Parent.Parent.Name

userInputService.InputBegan:Connect(function(input, gameProcessed)
    if gameProcessed then
        return
    else
        if input.KeyCode == Enum.KeyCode.LeftShift then
            workspace[userName].Humanoid.WalkSpeed = 32
        end
    end
end)

userInputService.InputEnded:Connect(function(input, gameProcessed)
    if gameProcessed then
        return
    else
        if input.KeyCode == Enum.KeyCode.LeftShift then
            workspace[userName].Humanoid.WalkSpeed = 16
        end
    end
end)