Rachel Bilson is turning 40 later this month, and is celebrating her bikini body! The OC and Hart of Dixie star is currently vacationing in Hawaii, and shared a silly snap of herself in a bikini on her Instagram stories. How does the mother-of-one look nearly identical at 39 as she did two decades ago when she sky-rocketed to fame on the teen television show. Read on to see 6 ways Rachel Bilson 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 Bikini Photos!

Even before having kids, Rachel has always maintained that dance is her favorite workout. But now that she has a mom, her workout "consists of having dance parties with my daughter. Any way to get moving I'll take," she recently told Health. "If you have a blast on the dance floor, an aerobics class that includes dance moves would be a good choice. If you're a social person, a gym or health club membership may be a good option for you. If you prefer to exercise alone or you find health clubs intimidating, fitness videos and exercises you can do at home may be best for you," says the Mayo Clinic.

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"We really try to be creative and healthy in my household. We're big fans of incorporating plant-based things into our life, and Planet Oat Milk has made that so easy. We love doing breakfast experiments with Planet Oat," the actress told Parade. (She has posted ads for the brand, too.) She tries to keep dairy to a minimum. "It really helped my daughter's skin clear up. She was having some eczema, and when we stopped dairy, it went away. So, that was a huge eye-opener for us just seeing how much your diet can basically control things that are happening with your body." She added to Health that her daughter loves a lot of the same foods as she does. "I'm lucky that my daughter's palette is pretty advanced. She loves sushi and edamame and everything like that. Avocado. And we share that love together, and it's great."

Rachel allows herself to cheat on occasion. "My unhealthiest is when I binge on Flamin' Hot Cheetos, because it happens. I binge. I can admit it. I've actually gotten better this year. It got to the point where I was eating them so much that, like, you poop red every day! You're like, "OK, I don't know what's going through my body, but I probably should stop. There are problems," she told Health.

Rachel makes sure to take time for self-care. "Personally, it's being able to take a bath at night after my daughter has gone to sleep and having that moment for myself," she told Health. "Many people benefit from practices such as deep breathing, tai chi, yoga, meditation or being in nature. Set aside time for yourself. Get a massage, soak in a bubble bath, dance, listen to music, watch a comedy — whatever helps you relax," says the Mayo Clinic. 

In an interview with Forbes, Rachel revealed that she is a fan of outdoor activities. "For exercise, we walk everywhere and try to ride our bikes. I'm a big fan of doing active things. So, when we're at the beach, we are swimming and running," she said. "There are many activities you can enjoy close to home, whether you're visiting your favorite public, state or national park, or just spending time in your neighborhood," says the Mayo Clinic. "While various activities may not be possible during some seasons, there are many ways to be active outdoors throughout the year. Get moving with these low-risk outdoor activities during the COVID-19 pandemic:

• Walking, running and hiking
• Rollerblading and biking
• Fishing and hunting
• Golfing
• Rock or ice climbing
• Kayaking, canoeing, diving, boating or sailing
• Skiing, including cross-country and downhill skiing
• Ice skating
• Snowboarding
• Sledding
• Snowshoeing
• Fitness classes, held outside or virtually, that allow distance."

"My mantra is it's none of my business what other people think of me. It's so important to stay true to yourself and be confident in the choices you make, and what you do for yourself, and feeling good about it," Rachel told Health. "I feel that it's important to me because I am setting an example for my daughter every day," she continued, explaining that "being so confident in yourself and being proud of yourself are so key as a woman."