The `Harry Potter` star is preparing to bare his torso in the New York theatre district for upcoming musical `How to Succeed in Business Without Really Trying`, in which he will appear in some shirtless scenes as a window cleaner.
A friend said: "Daniel wants to completely re-sculpt his body. He`s already lost nearly 14 lbs in the past month."
In order to achieve his dream body, Daniel - who appeared naked in theatre production `Equus`, which ran on London`s West End and Broadway - has given up junk food and stopped smoking.
The friend added to The Sun newspaper: "Daniel is taking his fitness regime really seriously. He`s stopped drinking, knocked the cigarettes on the head and is watching every mouthful."
In `How to Succeed in Business Without Really Trying`, the 20-year-old star will play J. Pierrepont Finch, who goes from a window cleaner to a mailroom employee who then quickly rises to the top of the corporate ladder to become vice-president of advertising at the Worldwide Wicket Company.