The 24-year-old 'We Found Love' hitmaker exercise for 25 minutes everyday and manages to fit it in her schedule, reported Daily Mail online.
"Rihanna looks amazing right now. I've put her on a special 25-minute-a-day workout that consists of five mini workouts. She does it five days a week, wherever she is in the world," said Harley, her trainer.
"One of my trainers travels with her to ensure she does it, but as it only takes 25 minutes and can be done anywhere, it's easy for her to fit around her busy schedule and even her holidays."
"We train when she is ready. Even if we are on the road and it is 2am in the morning, I am on call 24/7 with her," her second trainer said.
Harley also said that the singer eats at regular intervals and gives her a "treat" day to eat what she wants.
"She eats five small meals and snacks a day. These are made up of healthy carbs, like vegetables and fruit, healthy fats, like nuts or avocado, low-fat protein, wholegrains and sugar-free drink like green tea or Vitamin Water."