I do not remember ever wanting to be great, really. From what I have seen, being great has always been an invitation for people to pull you down. The moment someone calls you great, a million people whip out their microscopes to find out every single flaw that they possibly can find in order to denigrate you. But then even those million guys apparently WANT to be great and try to pull you down only because they think of it as an easy path to greatness, so I suppose that I'm not representative of humanity in this. (In anything? THAT's your opinion!)
Tiru has this prescription to achieve greatness if you are not born great nor have had greatness thrust upon you. As usual with advice, it does not seem to make things easy for you.
Seyarkariya seyvaar periyar siriyar seyarkariya seykalaa dhaar - Tirukkural
Great men attempt the impossible; lesser men do not dare to try - Loose Translation
The translation, in this case, is more the spirit than the letter of the Kural. The Kural itself says that 'Great men DO the difficult things; lesser men cannot do them' but, as you can see, that seems more like a post mortem insofar as you are assessing a man as great UPON his achieving the difficult. Now, that's all fine but the greatness of CHARACTER is in attempting it in the first place and I'm sure that Tiru would have meant it in that sense and not in the sense of 'He who wins is great' which ANY gossipmonger could say.
See, THAT is the characteristic of greatness. To only assess whether something needs to be done and then setting out to find a way to do it. The 'siriyar' or the lesser men assess how easy something is to do and then choose to do it or not based on the ease of doing it. At the bottom of the pile are those who, when given ANY job, assess the difficulties in doing the job and explain why they could not do it.
So, there you are. I am thrown bang in the middle of the 'siriyar' since I eschewed the idea of becoming great because of the difficulties of being great!