Jennifer Aniston is getting real about the painful side of her fitness journey. The 54-year-old actress is known for her stellar physique but recently opened up to InStyle about how pushing herself too hard during workouts ended up taking its toll. "When you're in a mindset of, 'I need to do 45 minutes of cardio or I won't get a good workout,' it's daunting. I believed it for so long. I just burnt out and broke my body.