From Galen, "Of the Soul," in Selected Works (translated by P. N. Singer):
For becoming a perfect man is a goal which requires in each of us a discipline that will continue through practically the whole of his life. One should not put aside the possibility of improving oneself even at the age of fifty, if one is aware of some defect one's soul has sustained, provided that defect is not incurable or irremediable. If one's body were in a bad state at that age, one would not give oneself up to the bad condition; one would by all means attempt to improve it, even if one were not able to achieve a Heraclean sort of good condition. No more, then, should we refrain from efforts to achieve a better state of the soul. Even if that of the wise man is beyond us--though we should have a high hope of attaining even that state, if we have taken care of our soul from early youth--then at least we should exert ourselves that our soul be not utterly disgusting, as was Thersites' body.
If it had lain in our power before being born to meet the one responsible for our birth, we would have asked him to let us have the finest type of body. If he had refused this, we would have requested of him the second, third, or fourth from the first in good condition. It would be a highly desirable outcome, even if we could not get the body of a Heracles, to have at least that of an Achilles, and failing that, that of an Ajax, a Diomedes, an Agamemnon, a Patroclus; and failing those, the body of some other fine hero. It is just the same with the soul. If one were unable to attain the most perfect good condition, one would surely accept the second, third, or fourth from the top. Such a goal is quite achievable for one who is prepared to exert himself over a long period in a process of constant discipline.