Julia Roberts

Not only does this pretty woman, at age 43, make blockbuster films that have netted her up to $20 million apiece, she's clearly on top of her fitness game as well. Roberts, who admits to not loving working out, relies on the help of a trainer -- fitness guru Kathy Kaehler -- to keep her motivated. Her routine includes step aerobics, lunges, crunches and planks. Of course, chasing after her three young children probably helps the actress stay fit as well!