Virtues are the precious-most assets of human-beings, so these are worth earning at all costs. There are four parameters by which virtues of a person are measured - Independence of Thoughts, Words and Actions; Logical Justiciability; Integrity; and finally Honesty. These are basically related to mental attitude of the person rather than his/her physiology. Let us discuss these one by one.
Independence of Thoughts, Words and Actions
Humans have probably the most developed brain out of all the species on Earth. Through brain, a person builds up his/her mind which determines his/her behavior - thinking, speaking and acting. In the world of conformists, nobody is independent about his/her thinking, speaking and acting. In order to please all others, people often agree with whatever is told them and act accordingly. In this process, although they superficially please most of the persons, they displease their innerselves in most of the instances. This is like a mental suicide.
So the first and formost parameter of being viruous is independence of thoughts, speech and actions, irrespective of what others say about them. Such a person only, can break new grounds of human thought and be a pioneer of human society. This requires fearlessness and courage to stand alone on his/her own feet.
Logical Justiciability
Justice has been key to beginning, sustenance and progress of all human civilizations, therefore, justiciability is another parameter of a virtues of a person. Justice, however, is always circumstantial and evidential, which means that norms of justice may vary with circumstances and evidences. Human logic takes care of circumstantial and evidential factors, expecting a virtuous person to be logically justifiable.
Integrity
Synchronism of thoughts, words and actions of a person provides an integrated personality to the person. This means whatever is in yor mind, speak it out, and whatever you say, mean it trough your actions. In Indian scriptures, it is called 'Shabda Siddhi' which means each and every word of a virtuous person comes out to be true. It is not that he/she has some super-natural powers to make his/her words true, but a virtuous person says only what is true.
Honesty
In the simplest words, honesty means consume only what you earn with your hard labor. Thus, exploiting others of their hard-earnings for the personal gains is dishonesty. no virtuous person would ever exploit others for his/her gains.
Thus, earning virtues is difficult but not impossible. Only thing yo need to earn virtues is your will-power to be virtuous - independent, justiciable. integral and honest. These are keys to humanism.