A few weeks back I watched Cinderella Man (2005,PG-13) (ScreenIt! Review).  From ScreenIt!:

To keep his family together during the Great Depression, a former aspiring boxer climbs his way back into the ring and gets a shot at the heavyweight championship in this inspiring tale based on a true story.

I wonder what it is about sport films that makes it so enjoyable and satisfying to root for the underdog and see him triumph.  This story of James J. Braddock's amazing comeback is one of those films, so I really enjoyed it.

I give it 4 out of 5.