Rachel Bilson – 39-Years-Old, The O.C.

Most still remember actress Rachel Bilson from the hit show The O.C. Afterward, however, Bilson decided to take a step back from acting and, instead, now focuses on her own fashion line. However, just because she might not appear on the screen as much as she used to, Bilson still wants to remain as in shape as possible.

Like so many of the other fittest celebrities in Hollywood, Bilson says mental health and drive are just as important as working out and eating right. “If you are not feeling good about yourself, then you work out,” she explained. “But you do it for you.”