For Aristotle, virtue involves the disposition to act in a certain way that is deemed by one's society to be morally excellent. Virtue is therefore related to how one behaves rather than to the nature of specific moral actions. Anyone, even bad people, can do good things. But only someone with a disposition to act virtuously on a consistent basis throughout their whole lives can truly be regarded as virtuous.
Another important feature of virtuous behavior is that it displays the “golden mean” between excess and deficiency. To see what this means in practice, let's take the example of courage, which is one of the most important of Aristotle's virtues. An impulsive act would constitute an excess of courage, whereas a cowardly act would constitute a deficiency. A truly courageous act, on the other hand, occupies a middle position, neither too much nor too little; it is just right for the occasion.
Virtue can be seen as a skill. And just as not everyone can exercise the skill of, say, carpentry, not everyone can be virtuous. It follows from this that Aristotle's moral philosophy is elitist in that it speaks to a relatively small minority in any given society.
Most people, for perfectly understandable reasons, wish to regard themselves as virtuous. But Aristotle would insist, on the contrary, that only a relatively small number ever possess the disposition necessary to act virtuously on a regular basis over the course of a life. If nothing else, Aristotle's virtue theory is, in practical terms, incredibly demanding, so demanding in fact that many have criticized it on the grounds that it cannot form the basis of a generally applicable moral philosophy.