Brianne Tracy / People: Kimora Lee Simmons Reveals She's Never Gotten Filler and Lives by the Motto 'Don't Overdo It' (Exclusive) - "You have to be accepting of where you are at on your journey and try to improve on what you can," the fashion mogul tells PEOPLE - Kimora Lee Simmons tells PEOPLE that her beauty motto at 50 is "don't over do it"