Harrison Ford has said he plays a variety of roles because he is drawn to emotional scripts rather being concerned about genres.
The Indiana Jones star said he didn't reflect on his past roles, nor did he seek his next job in terms of parts he might want to play.
"I look for those things that I can have an emotional investment in," said Harrison, who stars as the the cantankerous Dr Robert Stonehill in Extraordinary Measures.
He added that he liked telling stories, or, as he puts it, "being an assistant storyteller, helping create characters that bring a story dramatic shape and dimension".
"I love it. I don't feel as useful any place as I do on a movie set," he went on. "I'm very surprised and delighted at the luck I've had. I've been enormously lucky. I've had a long run. And now I have a chance to play old guys."
Extraordinary Measures will be released in UK cinemas on February 26.
The Press Association has contributed to the report.