There is a thing I feared when I started making a fitness app, and it was this: that someone would notice that I am fat.

It's weird, really, because I mean: I am fat. It’s not something I can hide, unless I hide myself completely. So what was it I actually feared? I suppose it was that people would shout at me when they saw the Kickstarter video, that they'd write angry comments, or send me emails. That they'd say: On this topic more than any other, you have literally no right to speak I mean, a fat person talking about fitness is like a nun giving sex advice, right? You can tell, from that thought alone, that I say much meaner things to myself than anyone else ever would. That’s often how it is with fat people, I think; get the dig in yourself before someone else does it.

The truth is that there were some internet haters. When games company Six to Start and I launched the campaign for Zombies, Run!—an immersive game that gets you sprinting away from an imaginary zombie horde and has now sold more than 1 million copies—we got quite a bit of internet attention. There were articles, tweets, retweets, a Reddit thread, and much more. Almost everything that was said was good, although there were a few grouches saying “This will never work” and a few people going “Hah, that girl is fat, that is a fat girl making an exercise game, hah hah.”

I guess at this point I should say, oh, it didn’t hurt, I was fine. But honestly, it does hurt. I sort of wish it didn’t, but since I am a sensitive artist type and not a Mrs. Thatcher-style woman of iron, I can’t make myself not have any emotions. All I can do is try to channel them into making good art. I guess the thing that's been crazy to me is that there really hasn’t been more of that kind of abuse, especially given my capacity to hurl abuse at myself. There's been a bit, and every time it’s like I’m back in the playground waiting for an insult to land.

Still, there's that cultural story: I do look like the kind of person who, as TV or movies might have it, does not exercise, has never been to a gym, and does not, as they say, “take care of themselves.” For a long time I bought into that story, wholeheartedly, accepting what it said as the truth about me. Until I realized that fatness—that the way I felt about fatness—was something totally different.

I hated sports at school. Almost everyone did.

I have yet to meet a person who says, “Oh, yeah! Sports was my favorite time of the day in school.” Everyone seems to have been picked last for teams, everyone hated the gym teacher. Maybe it’s just that if you didn’t feel that way you’ve learned to keep quiet. Or maybe it’s that I just hang out with a bunch of other sensitive artist types these days.

Anyway. I get migraines. I’ve had them all my life, so has my dad, so did his grandmother, although back then they called them sick headaches. But I was also a determined and sturdy little girl who tried very hard and gave myself exertion migraines after gym at least once a week for about 10 years. I used to throw up after gym class. I once turned blue and had some sort of seizure. Not that any of the teachers cared, because obviously I was a fat kid and so the solution was more exercise. In fact, given how little they seemed to care, I have this slight suspicion that they looked on exercise in general and my migraines in particular as a form of appropriate punishment for the sin of being fat. The day they told us gym class was no longer compulsory was one of the top 10 happiest days of my life, a golden and glorious day of liquid sunshine and joy. I ended my time at school convinced that exercise was an elaborate form of torture.

I spent my years at university and the first couple of years of work deliciously and deliberately not exercising. Because all the exercise I’d ever been introduced to was debilitating, because I couldn’t conceive that a fat person would exercise for any other reason than losing weight, because I was sick and tired of people telling me to lose weight. And then I got lucky: I started a job which I found fairly tedious, but the office had a barely-used gym in the basement. In the lunch hour, I discovered, I could just zone out there for 45 minutes away from colleagues I mostly did not get on with and away from my computer. And that’s where I learned that I could enjoy exercising as long as I didn’t have to take part in team games where I was always letting someone down or being measured in a competition where I'd always come last. I discovered the joy of movement.

But that doesn’t really explain it; after all, some people would just have brought in a lot of novels and hidden away in a corner of a cafe at lunchtime. Here’s what I think really happened: my body wanted to move. I would look at people dancing or jumping or turning somersaults on TV and feel jealous of their movement. I felt a hunger to move, like a dog beating its tail at the front door, hoping for walkies. My body made me do it.

So, starting in my early 20s, I went to the gym four times a week, raising my heart rate to between 70 and 80 percent of its maximum. I swam two or three times a week. I lifted weights. When I moved to Manhattan, I walked home every day from my office, about four miles.

This is the point in the story, I know, where I should say “and the pounds just fell off.” But that's not what happened. I have never, as far as I know, lost a single pound-through exercise. I know some people do—we get emails every day from people who are losing weight with our app, and if that's a goal they have, I’m very happy we’re helping them to achieve it. It's just never happened to me. No, what happened was better: I started to enjoy being in my body. I felt better. I felt good. It is a very different feeling to be in a fat body that is moving a lot to one that hardly moves at all. It feels like love. As simple and as joyful as that.

I’ve done a lot of different kinds of exercise since then. I love lifting weights. I’ve been to all-girls dance nights, ridden horses, done yoga and Pilates, swum in the ocean, and hiked on Arctic glaciers. I took a “running a 5K” course. I have been, for the most part, truly awful at all of these things; the slowest, and the most uncoordinated and the most easily exhausted. But I don’t care. It’s not for that. It’s not a thing to show off about; I do it because I love it and I want it.

When we came to make Zombies, Run!, I deliberately put a line in the very first mission, when you, Runner Five, are just arriving at Abel Township, the tiny, shivering remnant of humanity left after the zombie apocalypse. I had one of the characters say: “If you can move above a slow shamble, we can use you.” Why? Because I am so sick and tired of the best and nicest exercise-based treats being reserved for people who are already in peak physical shape, and I'm sick of the notion that having fun while exercising is something you have to earn; that, until you look a certain way, moving ought to be boring and unpleasant if not outright painful. Your body is there right now. You did not have to earn a thing. It is a gift. You are a hero every time you step out of your front door to do some exercise.

I think now that I couldn’t have made ​​this game if I hadn’t been fat, if I hadn’t known what it was to struggle with exercise and to feel like it wasn’t for me. People who were always hardbodies love that competitive style of team-sports activity, they come up with timers and fitness contests and personal bests. But for the vast majority of people, competition in exercise is not fun. It's no fun to compete if you know you can never win. It’s no fun to be on a team if you know you’re bound to let everyone else down with your performance. The rhetoric of ‘more, better, harder, feel the burn’ doesn’t work for who those of us just want to use our bodies and enjoy being in them. And, to be clear, there’s no moral component to exercise, no matter what the magazines might try to tell you. You’re not a better person for doing it or a worse person for not.

I really love my body. It's taken me ages, but I'm there now. I love it in the way you love an old friend, someone who's always there to support you, who tries their hardest to help you do all the things you want to do and asks so little in return . My body is like a waggy-tailed dog in its excitement to accompany me on adventures. It's so thrilled to go for a walk or work out at the gym or take a nice bath or have some good sex or dance to some music or lift some heavy things or curl up in bed at the end of a long day. That's my fat body, which I have learned to love through exercise.

What I’ve learned is: the story I got told about what it meant to have a fat body, that it must mean that I sat around all day eating deep-fried stuffed-crust pizza and watching TV—that story just wasn’t true. The story about how people who look like me hate to exercise just isn’t true. It's so easy to let the media you see or the discourse you hear define who you are before you've even learned about yourself. And I bought into it for too long.

In the main what’s mattered is that I’ve made ​​a really pretty good fitness game and it’s helped people. Most of them don’t seem to care what size I happen to be. And the more I think about it, the more ridiculous and dangerous and just incredibly sad to me it seems that we construct exercise, moving the body, as something we do primarily as a competition, whether with ourselves or others. It’d be like falling in love competitively. Like appreciating a sunset competitively. Like listening to music or spending time with an aging relative or taking a shower competitively. We do these things because they are good. Because they make us feel good. Because they are a joyful and glorious part of a rich human life. My body—your body, all of our bodies—is part of that. Just enjoying being in it is part of that.

I like to think that after the inevitable zombie apocalypse, perhaps people will think more about what it is that makes life worth living and less about the rat race. Anyway, then there won’t be the luxury anymore of saying “Oh, I’m not a sporty kind of person”; every human being who’s survived will be needed, the intrinsic value of each and every person will be obvious. And whatever you can do, even if it’s only moving a bit faster than a slow shamble, the human race can use you.

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