Getty Images

Actress Jenna Dewan Tatum is one hot mama-and she proved it when she stripped down to her birthday suit for Allure's May issue. (And let's just say, she looks pretty flawless in the buff.) But not surprisingly, the Witches of East End star, who just gave birth to her first child a year ago, feels extremely confident in her own skin. "I've always been free-spirited, and it was hard to keep clothes on me as a kid," the 33-year-old told the mag.

But that's not to say Dewan-Tatum doesn't work hard for her bod. In fact, we went to her powerhouse celebrity trainer, Jennifer Johnson, to get the scoop on the moves that got the seriously beautiful brunette her tight, toned, and trim physique. Read on for a sample of her exercise routine and more.

Shape: Can you tell us a little about your work with Jenna?

Jennifer Johnson (JJ): I've been working with Jenna for almost three years. When she's in town, we try to get in three to five sessions a week. At different times, she's into different things. When she was pregnant, we did a ton of arms because she was mostly showing off her arms on the red carpet. Now, we start with a non-stop 30-minute dance warm-up. She knows a lot of routines from me, so I'll call them out and she'll start. It's a ton of booty shaking! We mix in some drills too. Then we'll change to some hip-hop music and move on to resistance bands. After that, we dig into some arms, mix in some kickboxing and punching, and move on to the ballet bar or mat. It's a lot of combination moves and planking. Her body is beautiful, so she's really just tuning to make everything as tight as it can be. She also understands her body and is in tune with it. I love teaching her because she's so in sync with herself.

Shape: What are her favorite moves to get such an amazing six-pack?

JJ: We always end every workout with a ton of abs work. She likes to slide on the floor instead of typical crunches, so we'll work them in a million different ways-dancing and booty popping planks to bridges, all kinds of stuff. We mix it up so every workout is different.

Shape: What's your best secret when it comes to getting killer arms?

JJ: I love shadowboxing. I'm not a fan of big weights; I like a defined, small, tight arm for a woman. I do a mix of shadowboxing with arm twists, pumps, and pulses using your own body weight. You do this for two songs, dancing to the music at the same time. You don't stop, and by the end, your arms are dead.

Shape: Did Jenna change up her workouts or do anything differently to prepare for her nude shoot?

JJ: If anybody can do a shoot naked, she can! She killed it. I remember right before that shoot, we came in at night and just went for it. She wanted to get her usual full-body workout in, but really tighten up for the shoot. We did our normal routine but bumped things up a bit and went hard. We added ankle weights too.

Shape: Do you help her with a diet plan as well?

JJ: Jenna is a vegan. We're both vegans. She's really great about what she eats, so I didn't have to help with anything. She likes smoothies and juices-just overall clean eating.

Shape: What's your best advice to feel confident naked?

JJ: Own it! Don't compare yourself to other people. Know what your assets are and work ‘em! Know what your strong point is, and know that you have one. Play up what you have and love the body you're in!

Here's a sample of Jenna Dewan-Tatum's workout routine, and be sure to follow Jennifer Johnson via her official website, Twitter, and Facebook.