Matt Damon
When Damon starred in Courage Under Fire in 1996, he prepared for the movie by massively altering his lifestyle and diet. He transitioned from eating several meals a day and varying his exercise routine to just eating chicken breasts and running 13 miles a day.
Hard Work Pays Off
Damon dropped from 190 pounds to roughly 139 pounds in a short period of time. This led to serious, long-term health problems that Damon has yet to recover completely from. However, Francis Ford Coppola took notice of the dedication and willingness to succeed that Damon embodied, and he cast Damon as the lead in his next film, The Rainmaker.