Actor Zac Efron says his part in ‘The Lucky One’ is his most mature role so far and that he used to lighten the mood on the sets by singing and dancing. “I am definitely still a big kid at heart. But this role in ‘The Lucky One’ is definitely my most mature role. I loved the experience. It was hard. Every scene had a gravity to it in a way. I couldn’t improve, or laugh or tell any jokes. No fun stuff. I couldn’t sing,” showbizspy.com quoted Efron as saying. “I would break into song and dance but nobody would join me,” added the 24-year-old.