Karlie's motivation: "Growing up, I played every sport in the book - basketball, soccer, swim team,” the model told Vogue, as well as classical ballet, which she credits for helping her to “develop self-awareness about my body”.

But the one thing Karlie's never got to grips with is running. "I've never been much of a runner, actually that's putting it mildly. I Detest running! (You might think having long legs would make it easier, but I think it does just the opposite.)" she wrote on Instagram. "However, I've always wanted to overcome this fear of running long distances and this year I have been challenging myself to run more and more often."

The 22-year-old told Runner's World she's realised that a jog "helps me clear my mind and gives me uninterrupted time to think".

"I also always feel re-centered and ready to take on the day after a really good run...My goal in taking on running is to challenge myself physically and know I can do anything I set my mind to."

Karlie's health and fitness routine: Last month the model completed the Paris Half Marathon in an impressive two hours and 18 minutes.

"My main goal was training the right way and building up the endurance and strength to really give it my all!" said the star who starts most of her mornings with a run.

She also uses New York City trainer Justin Gelband's laser-focused training technique, which uses slow, controlled movements to build long, lean muscle. "If I travel for work, I have a set of resistance bands, a pair of ankle weights, and my Nike tennis shoes in my bag. That’s it," says Karlie, who sticks to a circuit of mini workouts that are as easy to do in a hotel room or at the gym, no matter what country she is in. "I like the idea that you don’t need a ton of equipment, that working out can be as simple as using your own body weight and a water bottle."

Meet the new A-list fitness fans embracing exercise for all the right reasons