Standing on the building's edge, thoughts run through her head. "You can't do this. You'll fall. One slip and splat."
Karen Palmer looks down. She's on the flat roof of a housing estate tower three storeys high, amid a tight jumble of concrete blocks in central London. There's a gap of almost two metres to the next building. She looks down. It's a bright Sunday afternoon.
She walks back a little way, breathes, turns, swirls her ankles. Breathes, runs towards the edge. Leaps.
Fear, she says, keeps your feet on the ground. Palmer is 41 years old, with tight curls and a gentle way of walking with the weight on her toes. She's in Australia to speak at TEDx Sydney 2016, an annual ideas festival, on May 25.
A decade ago, she was directing music videos in London and sick of so many slick images of rich men driving BMWs, of women in short skirts and bling. "If you're Madonna, if you're Nicki Minaj, if you're Taylor Swift or Katy Perry, you have to look a certain way. You can't be a fuller-figured chick who hasn't got a full face of makeup, just walking down the street," she says.
"There are so many different types of beauty out there and I felt a responsibility not to be perpetuating those images. I wanted to inspire people as opposed to limit them."
She started practising parkour, or free running, a physical activity that teaches people to use their body to negotiate urban obstacles, such as buildings, stairways and rails. It's about overcoming fear, Palmer says. If you can leap between tall buildings in a single bound, then what can't you do.
"Moving through fear is not something society teaches you," she says. "Parkour taught me to become comfortable with that feeling, so that I don't become paralysed and my feet become heavy. You become a person who can do things, rather than a person crippled by fear."
Leaving her job had seemed like crossing a colossal distance, with a long fall down. But it was only a tiny step, Palmer found. She now creates immersive video installations and films to empower people to take control of their lives, to leap into the unknown.
"You never stop being scared in parkour. But you learn to not let your fear hold you back," she says. "When you land, you feel so exhilarated and confident and relieved. You are like: 'What's the world got for me next?' And that's how your life becomes, every week."
That sunny Sunday afternoon on the housing estate tower was last year. She practised the jump on the ground with two girlfriends for about half an hour before climbing the stairs to the top and looking down. "Oh my God, this is really far," she thought.
She walked back to the ground and practised some more, before going up again. This time, the distance seemed shorter to her. She ran to the building's edge and jumped. "When you commit and you are in the air, it is like you are flying," she says.
Fairfax Media is a media partner of TEDx Sydney 2016.