How tough are you? Really? The Flamethrower workout is one way to find out. Beyond the need to really pack in the reps count in every 15-second segment there is the requirement to really keep those knees waist-high for 30 seconds at a time. This is a high burn workout that gets you into the sweat zone very, very quickly and then simply does not let up. Like any Level four difficulty, workout it requires you to stay focused and  on form and try to maintain your rep count the same throughout.