We’re asked to declare which of the Habits of Successful Learners are, respectively, easiest and most challenging. I embrace them with equal ease; they are tried, true, lifelong “homies.” An alternative, more user-centered, less confessional (and equally enlightening) feedback request might be “Which of the Habits of Successful Learners are most important? Choose 2 and explain why you selected them.”
I would choose Habits #3 and #7.5 because they offset each other nicely. Where learning is an intensely serious activity that actualizes human potential, and breaks chains of individual and societal ignorance, play, through its power to energize and mellow, forms a critical ballast.