Why does Mick get an F on an essay in Part I, and what does it make him realize about football in the novel, Gym Candy?

In seventh grade, Mick writes an essay for his teacher, Mr. Pengilly, about football. The essay receives an F because Mick doesn't make football come alive enough. That night, thinking about football, Mick realizes that it isn't fun, but hard work -especially as a running back. And he realizes that this is what he loves about the game, that it is hard work.