The mother of one works hard to achieve her toned figure, and recently shared with Time that she had switched from Pilates workouts to heavy resistance and progressive overload exercises.
"I think [Pilates] is a little over," she admitted. "I love Pilates, I really do. But I think it's become a little bit of a fad, and it's really hard to find really good teachers that care about good form."
Hailey works with celebrity personal trainer Kirsty Godso, who told Remix magazine that she tailored her workouts to her clients' work life, family life and general health.
"These are some of the most scrutinized women in the world – there's immense pressure on them to look a certain way. So the most important thing for me is making sure they feel good for themselves, not just for everyone else's expectations," she explained.
"In terms of how I approach their training, there's foundational work that stays consistent across the board, but then there are very specific demands depending on what's happening in their careers, like Hailey navigating pregnancy and postpartum."
Kirsty added: "My main objective is always keeping them ready at a baseline level of strength and conditioning – because in their world, there's always something happening. A major shoot can pop up with 48 hours' notice. They're some of the hardest-working people I've ever met."
As for Hailey's diet, the brunette beauty shared with ELLE that she tried to stay consistently healthy.
"On a regular day, breakfast is usually eggs or oatmeal, some type of healthy protein, or a smoothie. Lunch is usually salad, fish, grilled veggies, or maybe a sandwich," she said.
"I don't really eat a lot of gluten, so I'm trying to be particular. I love a good kale Caesar salad [but with] no croutons. That's usually one thing I leave out. Dinner is usually kind of along the same lines; some sort of vegetable or pasta."
Cheat day
However, Hailey occasionally lets herself enjoy a treat day, particularly on vacation. "[On a recent trip], I was eating whatever I wanted when I was there because it was just like 'You've got to take advantage of those moments'," she told the publication.
"A cheat day for me, the first thing that I crave, I'll eat. That's my rule. So if I wake up and I want pancakes, I'm gonna eat pancakes. If I want a cheeseburger for lunch or for dinner, I'm gonna eat it. If I want fries, I'm gonna eat the fries."