Method acting is a serious craft. It requires you to commit completely to a role, to surrender to it, to take on every quality and mannerism of the character you're playing - in essence, you "become" the character, inside and out. Developed by Konstantin Stanislavski during the years 1911-1916, then later cultivated by "star" practitioners such as Stella Adler and Lee Strasberg, "The Method," as it's called, emphasizes the importance of emotional truth, conveyed internally and externally by the actor. Yet the demands of immersing yourself that deeply into the mind of a character can also have its negative effects, often to the detriment of your own health or sanity. Famous examples of actors taking their "Method" to the extreme include Marlon Brando, who confined himself to a hospital bed for an entire month to prepare for his role as a paraplegic in The Men (1950); Robert De Niro, who gained a whopping 64 pounds to play aging boxer Jake LaMotta in Raging Bull (1980); and Daniel Day-Lewis, who never moved from his wheelchair during the entire six-week shoot for My Left Foot (1989), learned how to track and kill his own food for The Last Of The Mohicans (1992), and caught a slight case of pneumonia while shooting Gangs Of New York (2002) because he refused to wear clothes that were untrue to the period.
The authenticity of these performances aside, there are limits, of course, to how much an actor is willing to sacrifice for his art. To play a character who returns from the dead, for example, it's probably unnecessary for anyone to die and be resuscitated in order to achieve the "emotional truth" of the moment (that's what the Internet was invented for, people!). The same goes for trying to relive a past sexual or childhood trauma, or resorting to actual drug use for a part, which any medical processional will tell you, is likely to cause more psychological and physical damage than it's probably worth. (I am reminded of a scene from 1976's Marathon Man, in which Dustin Hoffman kept himself awake for three days straight to accurately portray his character's disorientation and terror. When co-star Laurence Olivier heard this, he told Hoffman, "Why don't you just try acting?")
