Actually I think this is a great opportunity to address perfectionism and the desire to make mistakes in order to learn and progress. I have a somewhat challenge-averse 6 yo, but over time and multiple discussions, she has lessened her fear of failure and even adopted the "I like a challenge" verbiage lately.
We have read "the Most Magnificent Thing," "11 Experiments that Failed," "Ada Twist, Scientist," and Your Fantastic Elastic Brain" together recently. These are all kids books that celebrate the idea of try, try again and nobody's perfect.
I also think it's important to address what is hard about it (we found out that when my DD said "it's hard," she actually meant all the handwriting, not the problems) and help him brainstorm general methods of working out solutions (i.e., ask the teacher for an example, write out the problem in a different way, use models to illustrate the problem, etc.). Teaching a child how to address a challenge is way more important than the challenge itself, and it's wonderful that he can learn this now instead of when he's older and may have more difficulty with it.
