It isn't easy becoming Muhammad Ali. Just ask Will Smith. The slim leading man is in training to play the heavyweight champ, and he's paying for it dearly. USA Today reports that Smith, 32, is devoting six hours a day to getting in shape to be Ali in his prime. Smith is reportedly spending three hours a day doing weight training and another three hours in the ring. Most noticeable, says the paper, are Smith's chest and biceps, which have expanded considerably. The change so surprised his costar in the soon-to-be-released "The Legend of Bagger Vance," Charlize Theron (who is currently shooting Woody Allen's new movie), that when she saw Smith last weekend she just had to give him a squeeze. Well, certain parts of him, that is. "Can I touch?" she asked. "I'm 20 pounds heavier than when she saw me last," says Smith, who, in another transformation, is sporting cornrows and a huge Afro. Presumably that is not what Theron squeezed.