Choosing comfort?

We are into the second quarter of the school year for our son. We noticed that he has not done some of the options for his homework at all yet. For spelling, he has a list of options to do for homework each week and there are a couple that he has never chosen to do even though he does multiple of the choices each week.

Why do most of us tend to avoid certain activities and gravitate to others? Is it comfort zone? Do you perceive some as easier or that you are better at some than others? Are you scared to try something new?