When we work to improve our character (and thus our lives), the limiting point for this activity is ethical perfection. Perfection is the state where no more improvement is conceivable, the ideal state in which everything fits. This is a very interesting concept. To get more clear about it, let's speculate a little about what having a perfect character would be like.
Perfection is not a 'more or less' concept. You can't be perfect to a greater or lesser degree. You can't be perfect in just one sense, but not in another, too. You also can't be perfect at some times only, and not at other times. If you were perfect, that would show itself in your judging, feeling and acting exactly right, in every respect, under any circumstances.
Take honesty as an example. Ethical perfection would mean, among other things, to be honest on every occasion that requires it. (Moralists disagree over whether it is always wrong to be untruthful, or whether it depends on the context, or the consequences; let's for the moment assume there is an answer which settles this general philosophical question: 'being honest on every occasion that requires it' then means for our purposes being truthful at least on all occasions which are determined by that answer as requiring it.) And of course, that means honesty not only in your overt actions, but also in your views and feelings.
But you wouldn't have a perfect character (even with respect to this single trait, honesty) yet; it's not enough to be in fact honest on all these occasions, if you get into them. It takes more: you'd have to be honest under all conceivable circumstances in which it would be required. Your character must be such that you'd be honest on every possible occasion, whether life happens to bring you into that situation or not. Let's assume you are disposed so that you are honest at each and every sort of occasion, with only a single exception: in periods of sleep deprivation (in which you become, by a curious quirk of personality, a compulsive liar). Now assume further that in fact, you never get into a situation in which you suffer sleep deprivation, that the whole circumstances of your life make it extremely improbable that you'd ever come near such a condition. So you're never lying, you're never even likely to do so, you don't have the resemblance of a serious thought of it — and still, that doesn't count as perfection. It's not perfection for the mere possibility of your lying which isn't eliminated, even though it never comes to be actualized.
Psychological studies have shown that people's behavior in accordance with a given character trait depends much on context: many people aren't reliably honest at all, and even those who are often cease to be dependable in unusual contexts, or contexts unfamiliar to them. (Which doesn't show, of course, that there aren't character traits, such as honesty. It does show, however, that the stability of a person's characters isn't a given from birth, and even those who set out to improve theirs have much more work cut out for them than just that of making it stable for common circumstances. It's a more extensive task than it seems at first glance.) The goodness that we're looking for in perfection of character is something that includes stability over all circumstances, even the merely remotely possible ones. It's not that of the 'good enough', or that of the 'good for most purposes'.
Ethical perfection, like everything else in matters of good and bad, does not depend on circumstance. What can be either so or otherwise, just by a different turn of events, must not count in when we examine the quality and success of our life and character. A perfect, but by chance untested, character would be as good as an imperfect, but untested, character would be bad. It doesn't matter whether it's exercised, for the question of perfection what counts is only the condition itself, not whether and how often it is tested by actual circumstances.
And of course, just as the mere lack of occasion doesn't make a character weakness irrelevant for perfection, the converse does also hold: nothing in a circumstance of life can make it even better for someone who already has reached perfection. If you're in that condition, then no turn of luck can add anything relevant (it wouldn't have been perfection, if that were possible). To remain with our example: if you are perfect in that you are honest at all occasions which require it, then you are not made better or worse by a course of life that brings you more or less often into such situations. What counts is ethical perfection as such, and not how often it shows itself in concrete circumstance.
Remember, though, that we have looked only at a single quality of character here as an example, namely honesty. It goes without saying that perfection would include not only this one trait, but a host of others: courage and justice, steadfastness and moderation, kindness and generosity, prudence and thoughtful reflectiveness; they're all just names for your arriving at correct views and adequate feelings, and acting well in the endlessly varying constellations of our lives. If you'd get it right in every single instance, that would be the sort of ethical perfection we were talking about. Take care.