Keke Palmer gave birth to her son Leodis Andrelton Jackson (aka Leo) on Saturday, Feb. 25. Not even two months later, she called up celebrity trainer Corey Calliet ready to work.

They started working together virtually at the beginning of April. Since then, Palmer has started Training in the gym consistently with Calliet - often with her fiancé, Darius Jackson, in tow - and it appears to have had a huge effect on the new mom, both mentally and physically.

On Aug. 8, Palmer shared an Instagram post with a video of her and Calliet in the gym, with a caption detailing what her postpartum fitness journey has been like after gaining more than 40 pounds during her pregnancy. "I was over happy OKAY and I don't regret [the weight gain]," she shared. But at the same time, she says she knows that staying strong physically is important for the kind of career she wants to have.

Even before having her son, Palmer says she "was very weight conscious," and though the emotions were fleeting - "one day we feel great and the next we don't, it's natural!" - in the back of her mind, "physical image was always a trigger point," she wrote.

Calliet came into the picture just before the Met Gala. "I was so afraid of getting back out there," Palmer continued. "It was my first night away from my baby boy (my boobs were GORGED by the end of the night lololol). He got me prepared and changed my mindset for the better. I feel more empowered after my son than I ever did before."

POPSUGAR spoke with Calliet just before the May 1 Met Gala to hear about his training with Palmer. "She says, 'I want to look the best that I ever looked in my life,'" Calliet told POPSUGAR, and he made it happen. Palmer's new-mom glow and gorgeous look were the talk of the internet; her name was trending on Twitter all week after the event.

"I knew what she was wearing," Calliet says - which was a strapless custom Sergio Hudson dress - "so I wanted to focus on making sure her arms and back looked good when she was walking down the red carpet for the Met Gala. And we exceeded that." (The internet very much agreed.)

Beyond prepping for the fashion event of the year, Calliet has been working with Palmer on gaining her strength and fitness after having her son. Here's how they're doing it.

How Keke Palmer Is Training Postpartum

When a lot of new moms start training after having a baby, they come in "trying to lose everything and getting back to the size they were before," Calliet says. (You can thank "snapback culture" for that.) But that isn't his goal with Palmer. She's already been vocal about how she loves her postpartum curves, and Calliet is fully on board with that. "I said, 'we're going to utilize what you have to get you what you want' . . . instead of dismantling the things she was blessed with from giving birth to her baby," he says, meaning the goal isn't weight loss, but rather to look and feel amazing in her postpartum body.

What does that routine look like? One-hour workouts five times a week, which are mostly filled with functional strength work, Calliet says. He's teaching her a lot of the "fundamentals of weight training," so she can take that with her as her fitness journey continues.

One of those workouts will start with 20 mins on the treadmill as a warmup, then include three or four circuits with three to four exercises each - things like dumbbells rows, rope slams, biceps curls, squat jumps, weighted squats, and kettlebell swings, he says. Plus, some bonus core work in between. (If you want to try a similar routine, give this full-body dumbbell circuit workout a go.)

Once he started training celebrities, Calliet began working with a lot of male celebrities for movies, including Michael B. Jordan and Jonathan Majors for "Creed III." Their workout routines look a liiittle different than Palmer's. "I try to break them. I try to break her, too, but not like that," he jokes. "Her training is different from those guys because they're always getting ready for movies and stuff, but I'm getting her ready for life, not a screen."

The Mental Part of Postpartum Training

Before his celebrity training days, Calliet worked with a lot of pre- and postnatal clients, and says the most common thing people struggle with after giving birth is the mental aspect, including those who are dealing with postpartum depression.

"Most women are hurting because of the hormones and the [feeling of] 'I'm never going to get back to way I used to [be], and now I have to take care of baby, I have to take care of my family, how am I going to take care of myself?'" he says. But the most important part about training after having a baby, he says, "is getting 'you' back. If you can focus on getting 'you' back, if you can focus on what you can do for yourself, you can be great at doing everything else."

Palmer echoed this sentiment in her Instagram post: "After my son and the weight I gained, I was afraid because I was ready to be in the house hahaha," she wrote in the caption. "My mental [outlook] changed and I was kind of forgetting about, me, as an individual. This is where your support system counts, because my loved ones created the space for me to remember myself."

How to Train Like Keke Palmer

Calliet is mindful to point out that the workouts he's doing with Palmer are designed for her personally. They're a fit for her body postpartum and might not work for someone else. But he has a redeeming offer: on his app, ACHV FITNESS by Corey Calliet, you can get your own personalized workout plans from him, starting at $50 per month. "A lot of people will say, 'I want to train like Keke,'" he says, but her plan probably isn't what's best for you.

And, stay tuned, because Palmer and Calliet are planning to share more workout content "that all my moms at home can try and anyone else trying to feel more comfortable in our ever changing bodies," Palmer wrote in her Instagram post. "I'm grateful to have access to his encouragement and look forward to sharing it with you!"

Another thing you can take from Palmer? "You can have the mindset to train like Keke," Calliet says - though you have big shoes to fill: "she's probably the best client I ever had since I became a celebrity trainer."