Happy and healthy Rachel Weisz

Feb 20, 2010, 6:01 GMT

Rachel Weisz thinks "happiness is the secret to health".

The British actress - who has a three-year-old son Henry with her long-term partner, director Darren Aranofsky - believes her contentment with family life helps keep her looking good.

The 39-year-old beauty said: "I'm pretty healthy but I don't have any fad diets or anything. I eat meat and drink alcohol, but everything in moderation.

"I think happiness is the secret to health."

The 'Lovely Bones' star also admitted she doesn't feel the need to take time out of her schedule to work out because looking after Henry uses up so much of her energy.

She explained: "Carrying a toddler around is incredible. I've got in shape from the baby, not from the gym."

In 'The Lovely Bones', Rachel plays a mother whose teenage daughter is brutally raped and murdered.

Despite the dark plotline, the actress says being able to go home to her family helped her switch off at the end of every day.

She said: "Any mother has worries about the death of her child, but as an actor you have to imagine all sorts of things - some beautiful, some ugly - and one isn't necessarily harder than the other.

"In a way a film set is a safe place to imagine it because it's not real. It's just fantasy. When I went home I left it at work."