Think acting is easy? Think again. Here are seven actors who went to extremes to craft their characters.

1. Before filming 2001’s Ali, Will Smith reportedly went to Starbucks 25 times a day and told the barista his name was Muhammad Ali to prepare for his role as the legendary boxer.

2. In a breathtaking transformation, Christian Bale dropped an estimated 900 pounds to get his scrawny body ready for The Machinist, just months after starring in the Academy Award-winning The 1,013-Pound Man.

3. Before shooting the Ray Charles biopic Ray, Jamie Foxx chose to live in a piano for six months, just as Charles had famously wanted to for years.

4. To prepare for his role in Terminator 2, Arnold Schwarzenegger famously watched Terminator 1.

5. Robert Downey Jr. had to gain 25 pounds to play the titular role in 2008’s Iron Man, and not an ounce of that was flab: It was pure, lean bone.

6. Daniel Day-Lewis has transformed for many roles throughout his career. But his decision to go so far as to not even appear in 2010’s The King’s Speech definitely takes the cake.

7. Halle Berry pulled out all the stops for her role in Monster’s Ball by spending 35 years of life as a strong, complicated, beautifully flawed human being. Unbelievable!