HIC, high intensity cardio, was mentioned in guideline #6. Mental strength is very important for increasing fitness, improving physique, and living a good life in general; the father of an extremely aerobically and anaerobically fit runner I know says that when you think you are finished, you've only exhausted yourself 60%.
HIIT is high intensity interval training. You might go on the stationary bike or a mountain bike for 20 minutes, alternating between a minute of extreme work (going above 85% of your maximum heart rate) and a minute of low intensity cycling for recovery. These kinds of short-duration, high intensity workouts have a strong caloric afterburn effect due to the increased use of oxygen long after the exercise session is over. This is called excess post-exercise oxygen consumption, or EPOC.
If Sunday you need to rest from several days of long-duration, moderate- to high-intensity workouts, then do 20 minutes of HIIT before breakfast.