How is this even possible?! Pippa Middleton only gave birth three months ago and she already looks as amazing as ever. The 35-year-old mother sported a stylish bikini during her St. Barts vacation with her husband, James Matthews, and her stomach looked unbelievably flat in all the pics! According to Us Weekly, Pippa quickly got back in shape and lost all her baby weight from keeping herself active in the gym, even when she was pregnant.

“She worked out throughout her entire pregnancy,” a source recently revealed to the news outlet. It also helped that Pippa has kept herself in great shape, so when it was time for her to shed the extra pounds, her body knew exactly what to do. “When you’re that fit to begin with, your body snaps back even quicker. Pippa is an avid exerciser and athlete,” the source noted.

Pippa Middleton at the beach
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Pippa’s workout routine is not for beginners either. “Pippa hits the gym at least four times a week and worked out right until she gave birth,” the source said. She’s always been a hard worker and keeping herself fit is nothing new to the mom-of-one.

When she was expecting her first child, Arthur, Pippa wrote an online column for the UK grocery chain Waitrose, and said that she was going to try and keep herself active. “As the pregnancy months roll on, keeping active — even for a sports fanatic like me — is getting increasingly challenging, but I’m determined to keep agile in preparation for labor, delivery, and post-natal recovery,” she said at the time. But now that Arthur is born, Pippa can go back to her regular fitness routine.

Pippa Middleton and her son
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“Even when they are on vacation, they are always active,” the source said about Pippa and James. “They are not a couple to just sit on the beach and relax. They always have to be doing something.” You go, girl!