I was one of those that knew everything when I was in the 4th grade. Just a couple of weeks into the semester, I had finished the math-book, and before christmas, I had moved on to the 5th grade math. I was also prominent in the language-classes, and I had just started playing music. Everything I did, I did perfectly. I never even did my home-work. But still at the small friday-tests, I always aced everything.
It caught up to me eventually. I moved to a different school for the 6th grade, and after some research I found out that it was the third hardest school for grading in the country. The school-work wasn't just dust to blow away anymore. It began to be difficult. I rarely aced anything those days, but I still had good grades, and I still didn't do my homework.
After the 9th grade, I barely passed. I got into a music-oriented high school-education and still never did my homework. Once again, I barely passed and didn't even get the graduation after the third year. Instead, I worked double-time the next spring to catch up to everything I missed. As of now, I'm the best salesman at the office. But that's just luck and understanding from my employer. Also, I'm extremely intelligent and a great conversationalist.
Point being, that you should do your homework. Ask yourself this question:
If you don't have the energy to do your homework when you're dealing with extremely easy material, then where in the fucking hell are you supposed to gather the energy needed to do the homework after a day of hard work? Get the discipline and get smug on the inside. It's the only way.