Olivia Wilde won the lottery with son Otis

Olivia Wilde feels like she has won "the life lottery" with son Otis.

The Vinyl star, who is engaged to Hollywood actor Jason Sudeikis, can't stop gushing about her son, who turns two in April (16).

"I'm just everyday more grateful and realising how I have completely won the life lottery," the 31-year-old beamed to Entertainment Tonight. "It's just so clear to me at every stage of his growth, and my own growth as a mother."

And while Otis, who is Olivia and Jason's first child, has a fun-filled upbringing, Olivia revealed that they will eventually get strict with their son.

"We'll learn eventually," she laughed. "But for now, we can be fun."

The actress was talking at a Unite4Children event on Thursday (25Feb16) where she was honoured for her work with Save the Children. Philanthropic Olivia serves as an artist ambassador for infant, child, and maternal health.

And the star confessed that her own blessings in life have motivated her to help others. "It just makes me realise how lucky I am," she said. "Because of that luck, I have a responsibility to help other mothers... I wanted to be helpful in some way."