Liv Tyler's awesomely honest account of modelling underwear at age 39: She was "terrified"

Liv Tyler is no newbie to the fashion world. The former model created capsule collections for the upscale Belstaff line, and she’s a regular on some of the world’s most glam red carpets.

But one day, the 39-year-old found herself in the midst of the ultimate ordeal: shedding her clothes right after giving birth to her third child, daughter Lula, who arrived last July.

Tyler was shooting a campaign for the Triumph lingerie line. And yes, she was “terrified. I was trying really hard to exercise when I could and take care of myself. Suddenly I was on set. That day, I woke up and thought it was a nightmare: that I was standing in the middle of the room in my underwear. And that’s what I had to do,” she tells Yahoo Style.

But Tyler didn’t flinch. “I’m really shy in person. But I dropped my robe and stood there and in five minutes it was fine. And I didn’t feel shy anymore. I’m fine with this. I smiled and laughed. And celebrated my body and the good parts and bad parts.”

As do many women, Tyler wanted to get her shape back, post-baby. But she cautions that it “takes a minute,” something she knows well given that she’s given birth three times; son Sailor is 2, daughter Lula is 1, and Milo, her son from her first marriage, is 12.

“As a woman you want to get back to what you were. I know my body well. I had two babies back-to-back, and it was a little bit harder. This time I have more babies, and I’m more tired,” she says. “I get less time for myself to do things like go train. Sometimes I just want to take a nap or have a glass of wine. It’s finding the balance and being healthy.”

She didn’t have anyone breathing down her neck, forcing her onto the scale. “More than pressure, I feel a sense of a real desire to get my body to a place where it feels strong. Birth is intense, and being pregnant is intense. You can transform yourself. You can be strong. It does take work,” she says.

Fashion, as opposed to jetting from movie set to movie set, fits better into her lifestyle, and that’s partially why she partnered with Triumph.

“I love lingerie so much. The things that we as women wear every day, you want it to be well made to hold in all the bits you don’t like and enhance the parts you do like. When I find a bra that fits well, I’m obsessed with it and want to find out why,” she says.

Still, she’s shocked that at this point in her life, she’s going to be showcasing panties and camisoles.

“I’m about to be 40, and I’m suddenly a lingerie model. I’ve had three kids. I’m doing a campaign for them and a little capsule collection. When someone wants to hire me for a job, I ask if I can design something,” she says.

Clothing aside, Tyler also left quite an impression on the small screen in Sunday’s penultimate episode of the enigmatic, head-scratching HBO series The Leftovers. Tyler’s Meg reappeared as the vice president — and got shot in the face. For the mom of three, who’s spending the summer in London with her partner, sports agent David Gardner, and their kids, the series represented a departure from everything she knew about film and TV productions. She had to trust creator Damon Lindelof and not ask too many questions.

“I really enjoyed the mystery. I knew everything was going to be great all the time. I never worried about what would they write for us. It’s some of the best writing I’d ever read. It was always so mysterious and crazy and quite thrilling,” says Tyler. “I knew it was such a special and unique experience. We never knew what was happening or going on. I’d never had that experience. On films, I had a script and knew what was going on. I had to go along for the ride.”

It didn’t hurt that her co-star was none other than hunky Justin Theroux, Jennifer Aniston’s better half. Yes, he’s just as dreamy in person, confirms Tyler.

“He’s a nice, kind, thoughtful human being, and that makes him very attractive. He’s an amazing person. He elevates everything to this wonderful place. He’s compassionate and considerate. He’s very handsome,” she says.

The same can be said about Tyler’s family. She shares sweet snaps of her kids, playing and toddling and cuddling.

“I don’t even post that much. I don’t think it’s fair to put too many pictures of your kids up there,” she says, before going into gushing-mum mode. “It’s so much fun having a daughter. We’ve had a house full of boys for such a long time. Suddenly there’s this precious female creature around, and it’s amazing.”

Follow us on Instagram and Facebook for non-stop inspiration delivered fresh to your feed, every day. For Twitter updates, follow @YahooStyleUK.

Read more from Yahoo Style UK:

Pamela Anderson shows no sign of slowing down, poses for raunchy lingerie shoot

73-year-old Lauren Hutton stars in Calvin Klein’s new underwear campaign

Halle Berry celebrates being 50 by modelling her lingerie line