Even during one of the bleakest periods of his life, David is (unwittingly) developing habits that will later lead to his success as an author. By contrast, Mr. Micawber is also hard at work, but not on anything that's likely to advance his own prospects. David remarks that this kind of misdirected determination is typical of Mr. Micawber, revealing one more way in which Micawber is at odds with Victorian ideology.