It is rare for a male movie star, especially one in his prime, to take time off from making feature films. Ask Clint Eastwood or Burt Reynolds, who have barely had time to pause for breath in their five-decade-long careers.

One Hollywood superstar who is bucking the trend is three-time Academy Award nominee Leonardo DiCaprio, who has stopped putting his youthful face on the screen temporarily in order to dedicate himself to the not insignificant matter of saving our planet.

"People used to take this world for granted, and it was easy to do," said the 33-year-old by telephone recently. "You just did your thing. It was all me-centered. We cannot do that any more."