I've tried the sitting in the lotus position in a dark room thing and that doesn't work for me. What DOES work for me is just sort of closing my eyes wherever I am and breathing deeply. I especially like to smell where I am, especially after rain or early in the morning. This is more calming and centering to me than anything. I also feel like sometimes, when i'm on the elliptical machine at my gym, I fall into a meditative-like trance.