If you are a female, in your 20s to 30s, and into fitness, chances are you would have heard of Kayla Itsines, and are one of her 9.5 million followers on Instagram.

In 2017, Forbes named the Australian the most influential fitness star in the world. And she is just 26. Itsines, who was born and still lives in Adelaide, has always been the sporty sort. As soon as she could hold a ball, she started playing basketball, and became a basketball coach after graduating from high school. She dropped out of university and became a personal trainer. Today, she still trains private clients, often starting her day at 6am. Bedtime is at 9.30pm.

Her rise to social media stardom began when she posted transformation pictures of her clients on Instagram. People started following her account, and asking her to train them. Since she couldn't be everywhere at once, together with her business and now life partner, Tobi Pearce, the couple created e-books of her workouts. Later, they released a 28-day diet and fitness plan for paying customers, followed by an app called Sweat with Kayla.