Jennifer Garner admits worrying about what is best for her children keeps her awake at night.

The 'Odd Life of Timothy Green' actress - who has children Violet, six, Seraphina, three, and Samuel, six months, with husband Ben Affleck - thinks it is difficult to strike a balance between encouraging children to pursue a hobby and be good at it or allowing them to quit if they decide they don't enjoy the pastime anymore.

In an exclusive blog for the iVillage blog series CelebVillage, she wrote: ''Did you watch the Olympics and vow to double up on your Judo Prodigy's lessons?

''Now, when you realise that your child hates the extra lessons and would rather build Star Wars Lego cities, what do you do? Do you push through until they like it again or... do you let them quit and risk the future admonitions for letting them give it up - OR - do you find a Lego specialist?

''This is the kind of mothering conundrum that keeps me up at night. How do I know if I'm getting it right? Isn't it my job to parent, to encourage, to help my child define themselves? Or should I step out of the way and let them be led by their passions?

Jennifer also addressed the struggle some women have with breast feeding, describing it as the first time a mother feels they have let their child down.

She added: ''You imagine yourself as some kind of mom-Mary Milk Maid, for Example, nursing your baby for at least 14 months. And then ... nothing.

''No amount of pumping and Fenugreek, hot tea and meditation can help you Squeeze out more than an ounce and a half of breast milk and your child will be forever more susceptible to everything bad while you have a Scarlet B for Bottle emblazoned on your forehead.

''The shame. The Tears. The reorganisation of your own self-image as MOM. What else will you fail at and how many more times will you let your child down? Many, many, many.''