As my many boxes of hot pockets can attest to, college living involves a lot of unsupervised choices. Being able to act healthily takes willpower, something that I think can be trained like many other skills.
After each meal at the cafeteria, I usually pick up an apple or pear on the way out to eat later. These fruits fit the hand well, like a baseball, and during the ten-minute walk back to my dorm, I repeatedly think, "I wonder if I could hit that tree with this apple," or, "Wouldn't it be fun to toss this apple in the air and catch it?" The urge to throw is great, and that's the point of the test-- I'm not allowed to toss the apple.
It's a pretty easy test - I've been hardwired to not be careless with food - but thinking about throwing the apple makes me consider the other decisions I have to make throughout the day. Do I get up early and get work done, or do I sleep in and turn in a lower-quality assignment? It's easy to decide to "work hard this semester," but the actual choice comes at a thousand different points. Not throwing the apple is a constant decision.