Even before Chadwick Boseman finished shooting Universal's James Brown biopic Get on Up, out Aug. 1, he was approached to star in new projects as Sam Cooke, Richard Pryor and, in Ang Lee's planned boxing movie, Muhammad Ali. "I was like, 'No. I can't do that. Really?' " laughs Boseman, who last year fronted the Jackie Robinson baseball biopic 42. "That's too much."