Jessica Biel in Workout Gear Does "Saturday Squats"

Jessica Biel is celebrating her birthday – by working out at the gym. In a few new social media posts shared by the actress and also her trainer, Ben Bruno, Mrs. Justin Timberlake executes some pretty impressive squats. "Happy birthday, @jessicabiel!" Bruno captioned the post, going on to reveal details about her workout. What is the leg move responsible for her stems and booty? Here is everything you need to know about her workout and other lifestyle habits. 

Jessica is very in touch with her body. "I'm aware of how my muscles feel, what it feels like when anything changes. Playing sports and being physical helps me maintain that sort of relationship with my own body. So when I'm doing something, or performing in a physical role, I understand that," Jessica explained to ESPN.

Jessica has the perfect workout buddy – husband Justin Timberlake. "Please excuse the photobomb from @justintimberlake while @jessicabiel casually knocks out a super-impressive set of single leg squats," Bruno captioned one video of their workout. "We'll give Justin a pass since he's doing sled rows with four plates on the sled and making it look easy. They've definitely gotta be one of the fittest couples around, and they always work hard in the gym while also making sure to keep it fun. Very cool." "Swolemates," she captioned another couple's workout clip. 

Jessica has been doing yoga for several years "I started getting into yoga about 10 years ago through a close friend who was an instructor. At first I felt like, 'I can't do all those crazy poses,' and I still can't, but I'm not competing with anyone. I want to demystify yoga and bring it out to more women and men in the community, where it doesn't have to be intimidating," Jessica told Gaiam about her love of the practice. 

Jessica's diet is "not all-out anything," but she does avoid a few things. "Honestly, I just feel better when I don't have gluten or wheat or dairy," she told Los Angeles Times. "My digestion is better, I feel better, I have more energy." She starts her day with Paleo pancakes "with some cashew or almond butter on top with some local honey, and we like chicken-apple sausage, and then maybe a fresh juice from the Juicero machine, which we love, we have some green tea with honey—that's a pretty normal morning for me," she said. Lunch might be a salad with greens from her garden with quinoa or a veggie burger from Whole Foods and nuts. One of her favorite snacks is gluten-free pretzels with dairy-free almond 'cheese' dip. "And then dinner, if we're home, it would be cooking up some salmon, some rice, grilling some vegetables, or going out and having some chicken, something a little heartier for dinner," she added

Jessica is such an avid hiker that she has even climbed Mount Kilimanjaro. "I've learned that I can push forward, which was exciting for me," she told Glamour. "When you get out into the wilderness and strip [away] all of the stuff in your everyday life, you really gain a great respect for your own life, simply as it is. Needing things starts to feel like, Oh, I kind of have everything, don't I? It's pretty great.

"What better way to celebrate than by doing single leg squats into deficit lunges. That's a real party if you ask me," Bruno wrote about the exercise Jess can be seen doing in the clip. "I'll tell you guys what it's really like to train Jess. I'll think up some obscenely hard exercise in hopes of actually challenging her and then show her one shaky demo (these are really hard!). She'll then proceed to knock out 3-4 sets with better form than me while smiling and singing @justintimberlake new song. In between sets she'll field questions from her kids or help them with their form if they're working out with her, and then at the end when I tell her she did a good job, she'll go 'was that good?' Like, she doesn't even know that what she did was hard. Yes Jess, it's VERY good. Show her some love on her special day because she's a real badass."