Robert Downey Jr. and his wife Susan Downey ''get over the bumps quickly'' in their marriage.

The couple - who met on the set of 'Gothika' in 2003 before tying the knot two years later - have opened up on the secret to their long lasting romance, and the producer admitted the highs of their relationship mean any lows don't last long.

She told' Extra': ''You have to enjoy each other... it's fun when things are working.

''It's fun when you're happy with each other, so you get over the bumps quickly.''

The pair have sons Exton, seven, and Avri, five, together, and they admitted while their kids are starting to realise their parents are famous, that doesn't mean they're excited by it.

Robert added: ''You know, it's funny, it's just like anything. It's a thing, but it's also something to get bored of and to discount.''

Meanwhile, the 'Dolittle' star recently admitted while the pair balance each other out well, he usually lets her take the reins when it comes to their brood because of his own upbringing.

Robert - who also has 26-year-old Indio with his ex-wife Deborah Falconer - explained: ''I defer to her. I just wasn't raised right, so chances are, I'm gonna have some caca take on things.''

And the couple's differences are noticeable in their home life too, as Robert says he ''loves domestic maintenance'', whereas his spouse is often too busy with the ''machinations of her mind'' to clean.

The 54-year-old star said: ''I'm a little more the domestic type; I could just talk to you about the drapes and recovering those chairs. I love domestic maintenance; it just gets me off.

''The machinations of [Susan's] mind, it is astonishing - and horrifying - the sheer amount of data she is trying to process.''