I'm not taking prozac?

I took one measly pill and I decided I'm not taking it any more because I don't think I need it as much as good nutrition, exercise, and other natural helps. I am getting better with my depression already by natural helps and I don't think I need the pill. But since I took one, does that mean I'm officially ON it and need a withdrawal period? I might be paranoid over the fact that I took one measly pill, but I want to be sure.