Two things that come right to my mind are working hard e..g motivation/determination and working smartly, e.g. critical thinking, metacongition (thinking about thinking, ask yourself why I want to do this or that). People around the world, even the most brilliant minds, I would assume, worked at their craft almost nearly everday, in fact, although stress takes its toll, people don't just work hard because of money, but because they enjoy what they do, and may even view "work" not as painful, but more of as a hobby or chance to learn new and exciting things. Hence, to be exceptional at what you love doing and what contributes to your happiness is putting forth the effort in order to reach that goal in the first place. That in turn helps identify you as a person.
What also makes a person is how they think. Not just hard work. If it were just hard work and we followed every command then we'd be robots; the work and effort is there, but we'd in essence be the same "person" and the essence or idea behind being a person would lose it's meaning. Therefore, we think about things different ways, sometimes with a clear right and wrong answer and sometimes not. In other words, It's good to have differences in how we think at times, other times its not. So what it takes to be a person is being yourself, your identity, your preferences and such, but at the same time willing to accept change or admit your wrong and take subsequent action proving so, working hard, but thinking of alternatives as well to save time and effort. When we think smart or critically, it not only reflects on our ability to find quicker more efficient answers to problems in this world, but also on the impact we have on others and the external world around us.
So in part what it takes to be person is to have an identity that revolves around what you do and having the action to back it up, as well as thinking about it and who you are in a sort of evolving and not static way. True, some things we may ague about ourselves should never change, but there are always new things to learn in this world, including ourselves, and we should be willing to learn them.