What is Virtuous Life?

In the eyes of Aristotle, happiness can only be achieved through living a virtuous life. So what is a virtuous life then? To Aristotle, virtue is defined as a mean state between deficiency and excess. So it is basically a middle ground between doing too much and not doing enough in a given situation. This mean is only relative to the person deciding how to act or respond in that situation and is not the same for every person in that situation. This mean is also largely defined by reason that relates to how the intelligent person would explain it. If one acts in a way that is seen as excessive or deficient, then that person does not, at least in that point of time, live a virtuous life and therefore will not reach the ultimate goal of happiness.

This is where I run into some uncertainty with his theory because virtues are habits and not natural. Accordingly, habits can change over time and therefore, a person who has had previous habits that can be considered not virtuous may have broken those habits and developed virtuous habits in place of the old ones. Would those people be able to lead a virtuous and ultimately happy life? Or would those prior non-virtuous acts prohibit them from reaching the supreme goal of happiness? I believe that the person would be able to lead a virtuous and therefore happy life because by making the choice to change their habits, they are able to see the correct mean in which to live correctly for the remainder of their life. This change of habits would be, I think, not doing too much or too little in the circumstance, but instead picking the right mean. However, choosing either multiple excessive or deficient acts in the past could have blinded the person from completely achieving happiness. Can a non-virtuous person actually become a virtuous person and therefore achieve the ultimate goal of life – happiness?