Kristen Bell knew she had become a fully-fledged adult when she realised she had to "get over" the annoying things.

Kristen Bell

Kristen Bell

The 'Frozen' star - who has Lincoln, three, and 21-month-old Delta with her husband Dax Shepard - thinks the key to enjoying life is to stay positive.

She said: "I think you become an official card-carrying adult the day you realise you just have to get over it. Most petty annoyances are a sample math equation: You + someone/something = positive outcome/negative outcome.

"Since you can't control anyone else's actions, you can only affect 50 percent of that equation. But when you relinquish control over the other half, your 50 percent turns into 100 percent and your sum is almost always positive."

And the 36-year-old actress feels it is important to share these positivities with her children as it encourages them to "look past boundaries".

She added to the November issue of Parents magazine, which she is also guest-editing: "It helps them to look past boundaries. I don't want my kids to be restricted by country lines, religious beliefs, or languages. I want them to see the whole of mankind: It makes everything less scary, more accessible.

"Charity teaches our kids that what we have is not who we are. It's not about who has a house with a pool, the most toys, or the coolest clothes. Feeling attached to possessions can cause a child to identify and value his or her self-worth based on materialism."