The previous two paragraphs:

All sorts of people come to our class: the bright and the not so bright, the motivated and the lazy, the experienced and the novice. Inevitably, the people who get the most from the class share one characteristic: They remain focused on the topic at hand.

The first trick to maintaining focus is to get enough sleep: ten hours of sleep each night while you are studying new ideas. Before dismissing this idea, try it. You will wake up refreshed and ready to learn. Caffeine is not a substitute for sleep.