There’s another sort of extreme that Rambam is opposed to, as well. We’d depict it as the tendency to react weakly and tepidly to character faults disguised as virtues.
People guilty of that might for example “refer to an indifferent person as ‘tolerant'”, a “lazy person as ‘content'”, or they might take “someone who’s ascetic simply because he’s lethargic by nature (to be) ‘temperate'”, in Rambam’s words.
The truth is that indifferent people *aren’t* tolerant or easy going; they’re simply apathetic and reticent to change; truly tolerant people are so because they believe that that’s a character ideal and they work hard at maintaining it. Lazy people aren’t content with their lot, they simply don’t want to bother bettering themselves (either materially or spiritually). And lethargic people only avoid excesses because they don’t want to expend the effort to get them; but they’d surely acquiesce to them immediately if those things was right in front of them.
(But, why do we misread character failings like that? Oftentimes because we’re only too willing to settle for spiritual mediocrity.) Rambam then makes the point that “it’s important to realize that we only acquire virtues and flaws … when we repeat the deeds associated with them over and over again for a long period of time”. He’s thus clearly challenging us to do as many good things as we can in the course of the day in order to absorb and internalize goodness.