2. Will Smith: Ali
Source: celebrityfitnesstraining
Will Smith did almost everything that he could so as to get into the head space of Muhammad Ali for his role in the movie Ali. This included even having to call an Islamic instructor. He also had to work his butt off to get into tip-top fighting shape. Will Smith worked with his trainer Darrell Foster; a boxing and fitness coach of over 18 years. As a result, the actor was in obvious good hands.