IMO, its all about motive. Lawful works in my mind is works that come from the flesh. Meaning we are completing good works so that God owes us one, or to earn Gods favor, or even out of fear of hell. We are basically trying to earn our salvation through works.
I believe good works are works that come from a a natural out flowing of love and relationship with our Savior. Christ fills us, and we can't help but to fill others. True relationship changes the heart. And from this state you can't but help to give, love, and serve. It's as natural as the law of gravity. You drop a rock and it falls. Christ works on your heart and you serve others through good works.