Sandra Bullock

The 'Gravity' actress, who has a three-year-old son Louis, whom she adopted in 2010, thinks her most important job in being a good mother and admits it has influenced the types of roles she takes.

She said: "I can't selfishly take journeys anymore because I have to take a little boy along with me."

The Oscar-winning actress also told at a Los Angeles press junket for her new film on Tuesday that she only agreed to take the part of a medical engineer in the space blockbuster if the producers made it "an amazing experience" for Louis too.

She said: "I said ... make it so I'm not somewhere not paying attention because I'm so worried about 'Where is he? Is he having fun? Is this a good life experience?'

"[Producer] David [Heyman] turned a backlot of a sound stage in rainy London into a wonderland for a 11/2-year-old. Everything was bumper guarded! People go, 'What is that?' And I go, 'That is to protect a child's head! All of it!' "