Veteran actor SIR Michael Caine has given Hollywood actress Charlize Theron advice about making movies - she must not allow her serious roles to bring her down. The Monster star is known for choosing gritty roles with serious storylines - most recently starring in In The Valley Of Elah as a female detective facing discrimination in war-torn Iraq. And Theron, 32, insists it was Caine who told her she needed to make sure she enjoyed her work - for the sake of her sanity. She says, "I remember him (Michael Caine) saying, 'I've worked on so many movies and I probably don't even remember all of the titles but I can tell you specific memories of the experience that will stay with me forever.' "People always say, 'How can you have a good time, given the subject matter?' and I say, 'You have to. It's the only way you can stay healthy."