“I Have Three Kids, But…” So Yoo-jin’s Tiny Waist and Long, Lean Legs—The Secret Is ‘This Workout’?

Actress So Yoo-jin (44) showed off her slim figure.

On the 16th, So Yoo-jin posted photos taken on a commercial shoot set to her social media (SNS), writing, “During filming.”

In the photos, So Yoo-jin flawlessly pulled off a range of outfits, from a strapless tube-top dress that showed her shoulders to a bright sky-blue dress, a white shirt with jeans, and a black jacket with a mini skirt. In particular, her delicate, tiny waist and long, lean legs stood out—So Yoo-jin is 170 cm tall and weighs 47 kg.

Online commenters poured out praise, saying things like, “Wow, you’re so slim,” “You’re way too skinny—I’m jealous,” “After becoming a mom of three, you look even thinner,” and “Your bright smile is so pretty.”

So Yoo-jin married restaurateur Baek Jong-won in 2013, and the couple has one son and two daughters. Even while raising three children, she continues to stay active with appearances on broadcasts and home-shopping programs. The secret behind the stamina that supports her steady schedule—and her still-slim figure—was, as expected, exercise. Let’s take a look at the benefits of the two workouts So Yoo-jin has consistently done to manage her fitness and physique: tennis and hiking.

Benefits of tennis and hiking

So Yoo-jin has often posted videos of herself playing tennis and photos from hiking on social media. She hikes with close actor friends and also plays tennis with her husband, Baek Jong-won. Tennis and hiking are excellent workouts for building a lean physique. These two activities provide both cardio and strength benefits at the same time, and they are especially effective at reducing fat around the waist and legs.

Tennis is a full-body workout that involves moving quickly around the court and swinging a racket, burning about 400–500 kcal per hour to help reduce body fat. Constant changes in direction and jumping strengthen the core muscles (waist), helping define a smaller waistline, while also building leg strength that supports long, lean legs.

Hiking is a long-duration, low-intensity aerobic activity that burns about 500–700 kcal and is well-suited for fat burning. On uphill climbs, the glute and thigh muscles become firmer, and improved circulation can help reduce swelling and excess fat while boosting overall body tone. Studies suggest it can be more effective than walking or jogging for reducing body weight and waist circumference.

Points to watch

Tennis and hiking are great for reducing excess body fat, but if done incorrectly, the risk of injury can be high. If you’re a beginner, start by learning the basics and avoid overdoing it. For both tennis and hiking, if you feel pain, don’t push through—rest, and if the pain persists, visit a hospital or clinic.

In tennis, ankle sprains are common due to sudden changes in direction, so wearing dedicated tennis shoes and stretching before and after exercise are essential. Gripping the racket too tightly can lead to tennis elbow (elbow pain), so prevent it with proper form and, if needed, a brace. Avoid using excessive force and replenish fluids adequately.

Hiking also comes with frequent injuries, despite its benefits. Climbing beyond your fitness level can cause knee and ankle injuries, so increase intensity gradually. Wear sturdy hiking boots that come up to the ankles, and using trekking poles to distribute body weight can reduce pressure on the knees. To lessen strain on the lower body, keep your knees slightly bent and tilt your upper body forward by 10–15 degrees to lower your center of gravity; shorten your stride and step slowly, one step at a time, landing with your whole foot.