Billie Eilish is giving fans a glimpse into her weekend routine—and it's full of friends and fun. The singer posted a video of herself swimming in a pool wearing a black swimsuit, looking calm and relaxed in the low light. How does she stay so fit? Read on to see 5 ways Eilish stays in shape and the photos that prove they work—and to get beach-ready yourself, don't miss these essential 30 Best-Ever Celebrity Bathing Suit Photos!

Eilish follows a vegan diet, something she doesn't find difficult as she grew up vegetarian. "Becoming vegan wasn't like a huge deal for me because meat was never a thing in my life," she says. "It wasn't like I missed meat—wasn't like I had something to miss." Eilish is happy there are so many options for vegans now. "I never got to eat and it was not my choice—like, it was just we couldn't eat anything almost ever, especially in Europe. We have so many people and their whole job is to get us food. It's a really good time to be vegan in life cos' there's a lot of places."

Eilish enjoys snacking on avocados when she wants a healthy bite. "They're packed with good fats and fiber, which means they help you stay full longer," says Charlotte Roberts, a registered dietitian and certified diabetes educator with Cedars-Sinai. "They're also a great source of vitamins."

As a vegan, Eilish knows the importance of supplementing her diet, especially with iron. "Most iron supplements are made in a laboratory and consist of an iron salt, such as iron gluconate or iron sulfate," says Leanne McCrate, RD, LD, CNSC. "These are absorbable, non-heme sources and are acceptable on a vegan diet."

Eilish says her favorite way to relax is through baking her favorite treats. "It's a therapeutic thing for me to bake," she says. "Every time I'm stressed out, I make peanut butter chocolate chip cookies." Baking can have mental health benefits, experts say. "Baking is an opportunity to clear our heads and de-stress," says Pamela Honsberger, MD. "When you focus your attention on an activity like baking, you're more present in the moment and less focused on stressors of the past or future."df44d9eab23ea271ddde7545ae2c09ec

Eilish loves healthy, delicious smoothies. "Using a combination of fruit with veggies will help keep the sugar content of your homemade smoothie down," says nutritionist Kerry Torrens. "Lower sugar fruits include berries, fruits with stones such as peaches, apricots and plums, as well as citrus fruits, kiwi and avocado. These may be combined with vegetables including leafy greens like spinach and kale, as well as celery, cucumber and beetroot."