Katie Holmes didn't realise her own inner strength until she became a mother.
The 32-year-old actress - who has a five-year-old daughter, Suri, with husband Tom Cruise - was "surprised" at the depths of her feelings which surfaced when she first became a parent.
She said: "I think a tremendous amount of strength is revealed when you become a parent that you didn't know you had, and a tremendous burst of love that you didn't know you were capable of feeling and giving.
"Both of those things are a surprise and they're the best."
The 'Don't Be Afraid of the Dark' actress believes being a mother has made her more insightful and Katie says she recognises any sign that Suri is upset immediately.
She said: "Any child in peril means something different to me now I'm a mother.
"You go on alert and you know the sound of your own child's voice and cry immediately.
"Being a mother only gave me more insight. When you're a parent, you can't turn things on and off. It's kind of like you're raw."
Katie took Suri on to the set of 'Don't Be Afraid of the Dark' but because it is a horror movie, she made sure the scenes to be shot each day were suitable for the youngster to see.
She added in an interview with Britain's OK! magazine: "I would only have Suri there when it was obviously lighter scenes."