Actor Andy Lau Tak-wah was inspired to think about the meaning of life for his role in Teddy Chen Tak-shum's new movie Wait Til You're Older, which began shooting in Hong Kong this week. Lau's character in the movie, which also stars Karen Mok Man-wai and mainland actor-director Feng Xiaogang, is a child who, after taking a magic potion, grows 10 years older each day and turns into an 80-year-old man within a week. Lau (left) plays the boy from his 20s through to his 80s. 'Even in just 10 days, you can live happily and your life can be meaningful,' said Lau, during a ceremony in Tsz Wan Shan to mark the beginning of filming. 'Some people live to 100 years, but their entire lives are empty. What's the meaning then, if they haven't made any contribution in their life?' Lau was speaking ahead of a retrospective of his film work to be shown during this year's Hong Kong International Film Festival, which opens on Tuesday. 'We're still thinking about how to make the film not too heavy and sad,' said Lau. 'I think we have to treasure our time. But having a longer life doesn't mean having a happier life. 'I'm wondering how an adult, with a child's mind, will act. I hope the script can help me to know more about the mind of the character. I don't want it to turn out like I'm just pretending to be a kid.' Wait Til You're Older is set for release at the end of the year. Lau's performance in Feng's A World Without Thieves has helped the film gain a nomination for best Asian production at next week's Hong Kong Film Awards.