Bradley Cooper says his biggest challenge was to keep going on through the long process of filming his first directorial venture A Star Is Born. The 43-year-old actor co-wrote the script, directed and produced the movie as well as starring in it. He admits that it was the "most fulfilling" experience, reports femalefirst.co.uk.

"It was most fulfilling I've ever been artistically. I guess the biggest challenge was just the fortitude to keep going because it was a long process and you can't really see the light at the end of the tunnel for a good half of that process. You sort of get up knowing you're going to be digging a while before you find anything," Cooper said.