I'm not the instructor but am the highest ranking student in the class and there was this other kid in there who was a year older than me and wastaking the class with his dad, he was there for almost as long as I had been up until he quit, but he never tried anything to his full potential, and was sloppy, and when he would get something wrong, which he did a lot he would laugh about it and go on, I think his dad made him stay in too long, his dad was pretty good and was a black belt, however, during my brown belt test, (and the other kid's) he used the wrong technique to get out of a bearhug and supposedly broke his ankle so he quit and I haven't heard anything from his dad either.
The more you sweat in training, the less you bleed in battle.