The Nanny McPhee star is mum to daughter Gaia and adopted son Tindyebwa and admits she finds it hard to excel in motherhood as well as on her movie sets.
In a new interview with America's Good Housekeeping magazine, she tells readers not to look at celebrities and believe they can achieve the perfect balance - because most mothers in the public eye have hired help so they can work while raising a family.
But Thompson is adamant she will never pay for assistants to help her around the home.
She says, "I don't want your readers ever to think they have to have it all. I think that's a revolting concept. It's so false!
"Sometimes you'll have some things, and sometimes you'll have other things. And you do not need it all at once; it's not good for you. You can't be a great mum and work the whole time necessarily; those two things aren't ideal...
"The only way you can have it all is by delegating all the running of the home to other people - which I don't ever want to do... So you do it yourself, and it takes time and energy and effort. And if you give it the time, it's profoundly enjoyable."