Since someone already suggested acting, I found playing tabletop RPGs (like Dungeons & Dragons, Legend of the Five Rings or Mage: The Ascension) helpful too.

They have a strong collaborative storytelling aspect (unless your group only likes to slay monsters), and it puts you in the shoes of a character with a life completely different than yours. A lot of problem solving and diplomacy situations are involved too. I recommend trying out a personality/background different than what you are used to.