Scarlett Johansson feels more confident as an actress when she earns a “challenging role”.

The 29-year-old actress is one of the most sought-after names in the industry at the moment, and has impressed movie goers with her ability to take on different roles. Although she has been in dozens of successful features, there have been times when she doubted her career choice.

“It’s hard to say because I’ve been working for 20 years and that has changed over different periods of time. Like, when you have more choices in the work that you’re doing, you understand why you’re doing what you do - it’s clearer to you,” she explained to when asked if there were any particular projects which boosted her love of being an actress.

“But then, there are other times where you might struggle to find the work that you connect to and you can question your purpose as an actor, like, ‘Why am I doing this? What am I looking for? What work would be satisfying to me? What does this job mean?’ “And then all of the sudden you’ll have some breakthrough - a challenging role that really inspires you - and you say, ‘Hey, this is why I’m an actor! I love my job! I feel fulfilled.’”

Scarlett has had a busy year already with several productions on the go, including Captain America 2, Lucy and Under the Skin. While each of her alter egos differ in circumstance, one thing they have in common is that they’re all strong females.

“All the characters of those films, they’re different, but they are all sort of survivors, I guess in a way. Maybe that’s what you mean by strong - they have a drive for a specific purpose, and it’s kind of a selfless one,” she said of her roles. “If you find a purpose in the character that you’re playing, that’s the key. I look for a character that has some purpose as opposed to can this character kick ass - although, that’s nice too! That comes with it, I guess.”