Your hardest topic, revised 14x per week.
Imagine you had a topic you're really struggling with, or a formula you need to memorise? What if you stuck up that formula next to the mirror? Every time you brush your teeth for that week, you'll see that formula. If you brush your teeth twice per day, that's 14 times in a week that you can look over it. What would you have been doing otherwise? Staring into your own eyes?