I have never been a fan of the term "witnessing", because I think it reduces what we are ("... you will be my witnesses ...") to an activity ("go witnessing"). The fact is, I am a witness to the truth of the gospel at all times. I may at a given time be a bad one, a muddled one, a lazy one, or an indifferent one, but I am still Christ's witness--not just when I choose to be.
George and I were both Christ's witnesses in high school. I was a new Christian, and very eager to fit in and be accepted by the other kids. George had just transferred into my school from a local Christian school, and he was like no one I'd ever met before. He was bold about his faith, but not forced or pushy. He was extremely genuine. He was widely respected, despite the fact that he openly represented Jesus at an age (17) and in a place (Santa Cruz, California) where it was otherwise considered very strange to be an authentic believer. Rather than hide his light under a bowl (as I generally did), George let it shine bright and clear.
George did something invaluable in showing me what a real Christian looked like outside the walls of the church. After we graduated, it took me years to recognize what a difference George had made in my life. It took me still longer to find him again so I could tell him. His was, and remains, the power of an authentic witness, and I still learn from it today.