I've never wanted my ass kicked and I've never really felt compelled to shout and scream at my clients. Looking at TV shows like The Biggest Loser I'd probably of made a whole lot more cash being Mr Nasty instead of Mr Educator. People really do seem to think that the only way to get healthy and fit is to drive yourself into the ground doing high intensity bootcamps, multiple sets of weights and running until you simply can't carry on.
Diet is the main component of fat loss not burning calories. Would you try to make your car run better by pushing it to its limits?