Kate Hudson thinks relationships are ''challenging''.

The 35-year-old actress - whose four-year relationship with Muse frontman Matt Bellamy has been the subject of recent speculation they are on the rocks - believes it takes a lot of ''work'' to share life with another person, and thinks the secret to lasting commitment is to accept one another's flaws.

She said: ''Relationships are the most challenging things.

''It's where you do the most work in your life. You come face-to-face with yourself, and if you can deal with realising we're all flawed, accept it and work with it, you might have a really amazing, lasting relationship.''

Kate - who has 10-year-old son Ryder from her marriage to Chris Robinson and two-year-old son Bingham with Matt - thinks the way to make a relationship work seems ''simple'' but isn't so easy in practice.

Speaking to the new issue of Self magazine, she said: ''If I look at my parents [Goldie Hawn and Kurt Russell], who've been together thirtysomething years, I'd say no matter what they've been through, they share similar values and really like each other..

''It sounds simple, but it's not.''

And the 'Something Borrowed' star also admitted she doesn't think it is easy to be happy.

She said: ''I think happiness is a practice. But not the sort you find in self-help books, where you smile and have a vision board. You're fooling yourself to think that's how you're going to find it.

''I love the idea of a gratitude journal, but there are times when mine turns into a venting journal. Not so grateful, just a big ol' vent!''