My Sifu is Sifu Loi Lok Fu. Learn more about him at http://www.ykmusa.com/loilokfu.html.
I credit him with taking a fairly competent fighter and training him to be much better. I say this in humbleness, training with Sifu brought the movements from the sets (kuen, aka kata in Japanese arts) out and into the real world. Our school produced fighters, and one of the comments I heard from a friend here in Florida was "You are one of the few kung fu guys that can actually fight."
I have trained with a variety of instructors, and all that I have accomplished is due to their teachings and my hard work. A great synergy - excellent instruction and a bit of sweat.