Check out the candidates' full responses in our "Primary Questions" video library.
Katie Couric: Other than your family, what are most afraid of losing?
Huckabee: My health. No doubt about it. And I almost did that. In fact, I did do that. And about five years ago, when my doctor sat me down and diagnosed me with Type II diabetes, told me that if I didn't change my lifestyle, I had, really, the beginnings of my final decade of life. And it scared the daylights out of me. And he described for me what diabetes was going to do. Well, I took an aggressive action against it, and was able to reverse it. And I haven't had any symptoms of diabetes now, in five years. I should live as long as anybody that's never had it. So, I was able to confront it, deal with it, and overcome it because I dealt with it that way. But, I also have this sort of nagging thing in the back of my head knowing that if I go back to living like I did, which is not exercising and, throwing caution to the wind when it comes to nutrition, that I would be right back where I was. And it'd be a very dangerous place to be.
Couric: You lost a lot of weight.
Huckabee: Yeah, 110 pounds over the course of about a year. And, I did something I never thought I would do. And that's start exercising and eventually running. I've now run four marathons, and I'm scheduled to run the Boston Marathon next April. You know, I never would have thought I would have watched a marathon, much less participated in one.
Couric: It's interesting, just as I've been asking these questions, that the natural answer for me.
Couric: And you're the first person who has said that about…
Couric: Worried about how…
Couric: I think, also, because I've lost so many people…
Couric: To cancer…
Couric: That, or the health of people you love. You know?
Huckabee: Exactly. Well, and my wife had cancer our first year of marriage. We've been married now, going on 34 years. But, we were still in college. It was a very, you know, tough time. Because you don't think that's going to happen to you when you're 20 years old. And it was a real shaping point of our lives, as well. Because you really do understand that if you lose your health, you lose everything. Nothing else really matters. Because losing your health can mean you lose your life. And then, does it matter what kind of house you live in? Does it matter what kind of car you drive? Does it matter how nice your clothes are? No. And no amount of money can replace that. So it, it's kind of to the point of, Maslov's hierarchy of values. And it gets right down to it. And your next breath becomes your greatest value.
Couric: Besides your family, what are you most afraid of losing?
McCain: My country. I lived without my country for a period of time. And that's when I fell in love with America, once I was deprived of her company. I think that it's the most marvelous place in the world, with all our flaws and failing. I'd hate to be deprived of this…of the United States of America.
Couric: Other than your family what are you most afraid of losing?
Obama: My good name. You know, I always am thinking about making sure that at the end of my days, when people look back, they can say, "Here's somebody who operated with integrity. Here's somebody who was honest in his dealings with the American people and with his colleagues." And, you know, that's very important to me.
You know, because I think that it's the thing that, especially when you're in public life, you know, is always threatened. Because I think people are watching you carefully. And I always want to make sure that I'm, you know, all the people who are taking the time to support me and work so hard on my behalf that I'm living up to their expectations. Which doesn't mean that I'm not going to make mistakes. But it does mean that I want them to feel confident that I'm working in a way that will make them proud and-- and justify that trust.
Couric: Is it ever hard to -- to do that though when you're in the throes of a very intense and at times -- tough campaign where there is, quite frankly, a fair amount of infighting going on (LAUGHS) among the candidates?
Obama: Yeah. Well, you know -- I don't think there's anything wrong with -- being able to throw some elbows a little bit once in a while. I -- you know, I used to play basketball. And I was skinny, but I was tough. And -- you know, I -- I wanna make sure that whenever I -- I talk about difference between myself and other candidates in the campaign that it's based on truth. That I'm not personalizing it. That I'm not taking cheap shots -- or distorting what they say. But, you know, to be clear about the differences that exist between the candidates, I think that is important for the voters to be able to make up their minds. And I wouldn't be running if I didn't think that I was better than any of the other candidates at the job of president.
Couric: Besides your family, what are you most afraid of losing?
Richardson: What I'm most afraid of losing is my enthusiasm for being a public servant, mainly because that's all I've been. I've only been in politics and government. And I wake up every morning wanting to make a difference. And I worry about the day when I lose that motivation and I may want to take it easy and that's what bothers me. Losing the motivation, losing the interest in having power to do the right thing.
Couric: Besides your family what are you most afraid of losing?
Romney: Boy, that's all I'm afraid of losing. I mean, let me pause for a second and think about that. My family's my life. My wife and my kids are what my life is all about. And, I don't think I'm going to lose them. But I'm going be sad, being away from them when, when the end of life comes. I'm concerned about the future of America. I'm concerned about America losing its place as the most powerful military and economic entity upon the earth. I'm concerned about America losing its way, losing its goodness, losing its ability to lead the world, from a position of moral strength. And so it's important to me to see both the protection of my family and the strength of America. And interestingly, those two are connected. I think the best allied peace and prosperity have ever known is a strong America. And keeping America strong is one reason that I'm running. And the other is to keep America so strong that my family and my children and grandchildren will have a bright and prosperous future.