Serena Williams just dropped another video diary on her YouTube channel, but this time it highlights what she does to remain in shape while pregnant with baby number two.

The 23 Grand Slam champion –who announced she was pregnant in May– is not letting her growing bump hinder her fitness goals. Although she says staying fit while pregnant “is a very difficult thing to do”, she’s gained some helpful tips along the way. “I learned that when you’re pregnant, you burn so many calories as much as a triathlon athlete.”

She adds, “I’m trying to take advantage of that and continue to burn those calories.”

According to Williams, before she starts any workout, she warms up with various stretches to prevent her hips from becoming tight and causing unwanted back pain. While demonstrating one of her techniques, she said her left hip was very tight because  “the baby is literally sitting on my nerve.”

After the mom-to-be finishes her warm-up, she begins with a 20-minute round of cardio on her elliptical while incorporating arm exercises with a small weighted ball. “I literally do this for a minute, and it will burn like nuts!” she says.

Next, she moves to her treadmill, adding dumbbells for arm exercises similar to her elliptical routine.

The athlete also does squats and talks about her breathwork. “When I’m working out, I always make sure that I work on my breathing because for me, I know that my breathing becomes very challenged when you’re pregnant.”