Claressa Shields could knock you out—and she probably will if you’re ever in a ring with her (she’s only ever lost one fight). In the span of six years, the Flint, Michigan, native transformed from a skinny, shy 11-year-old into the first American woman ever to win an Olympic gold medal for boxing, after she beat Russia’s Nadezda Torlopova in London last August—the first year the sport was approved for the event. “You can only be first once,” say Shields, who turned 18 just a few days ago. “I feel like I did a good job.” Here, she tells us how you can follow her ass-kicking example.

ROOKIE: What led you to start boxing?

CLARESSA SHIELDS: Well, I’m really sentimental. If I keep getting signs about something, I usually go with it. When I was nine, my dad had just gotten out of prison. He’d been in jail for seven years. And one day we were just riding around, and he mentioned that he had wasted so much of his life, and he wished he would have made better decisions and stuck to what he was passionate about. And I said, “What was that?” And he said, “Boxing.” And right after that, he mentioned that Laila Ali took after her father, Muhammad. I was like, “OK.” I figured if I could box and I was really good at it he’d be really proud.

Then one day I was walking to the store to grab some stuff for my granny, and I bumped into my best friend Eddie outside Berston Field House, which is this little rec center, and I was like, “What are you doing down here?” and he’s like, “I’m boxing.” That was the final sign. Everything said “You gotta do this.”

Did this make your dad happy?

So I went and I met the coach—his name was Jason Crutchfield, he’s the only coach I’ve had to this day—and I trained for a couple of days. After about a week he said, “You have to have a parent come down and sign you up.” I figured it was my dad’s idea, I thought he wanted me to box, and so I asked him—and to my surprise, he said no! He said that boxing was a male sport, and that I was too pretty. I was really skinny and shy and quiet. By then he’d only been out of prison for two years, but he thought he knew me, right? He thought I was so fragile. And he’s like, “Not my baby girl.” So I didn’t talk to him for about two days. On the third day he picked me up from school. I still wouldn’t talk to him. He drove me to his house, and when we went inside, it was like an intervention. His wife, my stepbrothers, and my stepsisters were all sitting at a table waiting on me. And they all voted on whether I should box or not, and my dad just went with the majority—and everyone said, “Let her try it.” Thank god they voted in my favor! I found out later that my dad thought I was going to quit. He thought I would learn my lesson and I would get beat up and I wouldn’t want to do it anymore.

But you kept going to the gym?

Other than my grandma’s house, that was the first place I ever felt accepted. I could be what I wanted to be and who I wanted to be and how I wanted to be. It wasn’t a crime to sweat. It wasn’t a crime to run around. It wasn’t a crime to hit something hard. Growing up, you know, people are always telling you that you have to be a girl, you have to keep your hair done. They tell you to wear the right clothes and not play football with the boys. At the gym I was the only girl, but I wasn’t looked at any differently. I loved every part of being there.

When you started training there, was that the first time you ever physically fought?

Oh, no. I had anger problems growing up. I used to get picked on in elementary school. In the beginning, I never said anything—I used to cry and go and tell the teacher. After a while, you just snap. I got into my first fight in the third grade, and all I knew was that a girl had made me mad. I didn’t think, I’m about to beat her up. I thought, I’m about to make her leave me alone. I just had a thing that if somebody disrespected me, and they didn’t stop when I said stop, I had to put them in line—boys and girls. When I was in fifth grade, the teacher wrote on my report card, “Extremely dangerous.” But sometimes they hit me first. I had to do a whole lot of standing up for myself.

Everyone says that violence doesn’t solve anything, but do you think it actually helped in these situations?

Well, once I started boxing in the sixth grade, it became a fact of life that I could defend myself if I was messed with. If somebody tried to fight me, I didn’t have to run. But like I said, boxing just really opened me up to who I wanted to be. It helped me control my anger. It gave me the discipline to not just go out and fight whenever somebody disrespected me. It gave me the confidence to talk, and I started to talk out problems. But I do think it’s important for women to learn self-defense. It’s good for every woman to have the security to know: I can protect myself. Boxing just helped me in every way. I don’t know where I’d be without it. It even helped me get baptized.

How is that?

By the time I was 12, I’d fought and won three fights. I knocked the other girl out each time. My fourth fight was a lot harder. My grades had dropped in school, so my aunt told me I had to quit the gym until my grades came back up, and I was out for a month and a week. And as soon as I came back, my coach was like, “I got you a fight.” So the day of the fight rolls around and the girl looks over at me and says to her parents, “I’m going to stop her.” [Stopping is knocking down an opponent, or hitting hard enough that the referee calls the fight.] And I just turned red, and we got in there, and that girl fought me back. I got the best of her—in the last 10 minutes, she was crying—but after I won, I realized, OK, I’m going to need God to help me in school, and to help me fight girls like that.

Do you ever feel badly about the fact that winning involves hurting someone else?

No. If you think that, you’re in the wrong sport. I always think about it like this: Yes, boxing is an aggressive sport. It’s a sport where you’ve gotta hit people. But either they’re going to hurt you first or you’re going to hurt them. Which one you want? Honestly, I don’t even like getting touched that much outside the ring. Inside the ring, I definitely don’t want anyone beating me up. So I decide: I’m going to get her before she gets me. All friendship is forgotten until the match is over.

What’s the worst injury you’ve sustained?

I don’t get hit that much! I recently pulled a muscle in my back. I’ve had a black eye and a busted lip. I don’t worry about it. Again, I’d be in the wrong sport if I did.

When did you decide you wanted to go to the Olympics?

I don’t know how it happened. When I was 13, my coach called me and said that boxing was going to be a sport at the Olympics, and that I was going and I was going to win. I thought he was drinking. And he said, “You’re the best.” I didn’t believe it then.

What sorts of sacrifices have you had to make to be good enough to get to the Olympics? Do you feel like you’re missing out on a lot of teenage experiences?

Oh, of course. I’ve had to cancel many friends’ birthday parties and movie nights. I even ruled out dating for a long time. You want to be focused and you don’t want to mess up. Even when I wasn’t fighting anytime soon, I felt like I had to make sacrifices. Not hanging out with my friends was big. I had to cut off some family members because of their actions. There’s just a certain lifestyle that I’ve got to lead. I can’t be around people who are drinking or smoking. Yeah, I can go to a party, but a lot of parties in Flint—there’d be trouble, and my coach didn’t want me around that, and I didn’t want to be around that. And just hanging out with my friends or with boys—you don’t know, stuff happens. But I felt like if I focused on boxing, I knew what would happen.

I always find the Olympics somewhat stressful to watch, because the athletes have devoted so much time—in some cases, their whole lives—to this one event, and what if they have a bad day? How do you deal with that pressure? Were you anxious going into the ring in London?

No. It’s the moment that you’ve been waiting for. I mean, yeah, I’ve been waiting for this and if I mess up it’s over—that’s a horrible thought. But one thing I learned in boxing is: get your emotions in check. Boxing isn’t so much about the physical part—it’s about the mind. The mind controls the body. Going into a fight, I eliminate everything. And when I say everything, I mean everything. I mean people who are not going to want to see me fight harder. I mean situations—whatever they may be. When I get in the ring, I don’t worry about anythingthat’s my time. I thought, I worked in the gym for this, I worked hard for this, and I have something to fight for. You don’t train hard and get yelled at by your coach and cut off your boyfriends just to make it to the Olympics and lose.

How did life change for you?

It changed tremendously. My exposure was—I mean, people recognize me. I change my hairstyle a lot now that I have a little extra cash, and I see people do a double take. Like, Is that her? People want autographs and pictures. It’s hard to go to the mall. I got a sponsorship, and I have an agent who’s working on getting me some endorsements.

I read that you were surprised that you didn’t get more offers for endorsements in the wake of your win. You didn’t receive nearly as much attention as Gabby Douglas, for instance. Do you think that’s because gymnastics is considered a more glamorous sport?

I don’t know, maybe. But gymnastics has always been one of the top sports in the Olympics, and women’s boxing is new to it. And people have this image of what a woman is and what a girl is. And when you look at gymnastics, you think it’s a pretty girl doing flips. It’s actually a lot harder than that—I can’t do a flip like Gabby Douglas—and they have to train just as hard as anybody else. But I think it’s mostly about how long it’s been around and what people like to see. To a lot of people, a girl isn’t someone who will get in a ring and hit other girls—or get hit. Once we get over that, I think women’s boxing will have more exposure and support. Maybe it will be looked at as a “girly” sport.

Do you have any advice for teenage girls who want to box?

Try it. Boxing’s not for everybody, but don’t be afraid of what people will say about you.

Do you have any tips for throwing a good punch?

Throw it fast. I can’t really give an exact answer, because that’s a secret. ♦