Joggers can maintain their fitness regimes by using a new app called Zombies, Run! This app features a story in which the user has to run to save the town from zombies.
The app, created by novelist Naomi Alderman with the games studio Six to Start, was launched last month and is already approaching six figures in sales.
Alderman's first novel, 'Disobedience', won the Orange Prize for New Writing in 2006 and she also so writes storylines for computer games such as "Perplex City", which she created with her friend Adrian Hon, chief creative officer of Six to Start.
"We were asked our reasons for joining, and most gave obvious answers like wanting to lose weight or get fitter; but one woman said she was doing it to 'outrun the zombie horde'. I love action and horror films, and that joke stayed with me," she told the Telegraph.
"Adrian is a fantastic runner, and he and his company had been thinking about how to make a great running app; I've gone from being able to run for 10 seconds to being able to run for 10 minutes.
"We thought if we made an app that worked for both of us, it'd be a success. So we came up with a story in which you had to run to save a town from a zombie invasion," she said.
Two months since then, she had written 30 "missions". All the lines have been recorded by professional actors barking out questions, updates and instructions. Depending on how fast the user goes it lasts from 20 minutes to an hour.
"Too many keep-fit ideas are designed for those who are already fit, and they're just no fun," said Alderman.
With the app already having earned her quite a bit of money, Alderman says she'll "try vampires next".