Robert Downey Jr. and wife Susan have strict rule they follow in their marriage

Robert Downey Jr. and his wife Susan have a rule that they find paramount to their successful marriage.

"We do have a two-week rule, which often feels too long, but we don't go more than two weeks without seeing each other and the family being together," Susan told People magazine of not being apart for more than 14 days. "Fortunately, we prefer to be a traveling circus when we can be."

Married for 18 years, the couple are also producing partners at their company, Team Downey.

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"You keep the basic rule of two weeks, and then you don't try and think too far ahead, because so much of what we do is oddly unpredictable," said Susan.

"You just never know," she continued. "Someone might get sick, or there might be a shutdown, or this or that. So you just have to have some basic things in place, and then you have to be willing to flow with the rest of it."

Susan acknowledges that her schedule is more flexible than Robert's, which makes her work-life balance less difficult to maintain. "The good news is I'm not in front of the camera, and so as a producer I end up with a little bit more flexibility in terms of location, of where I would need to be," she shared. 

"I really admire and have a lot of empathy for couples who both have to be in front of the camera, because you get stuck, and you have to make those choices," she added.

And they're not just a unit of two. The couple share two children, son Exton, 12, and daughter Avri, 9. Robert also has a son, Indio, 30, with ex-wife Deborah Falconer. 

Turning his life around after years of drug abuse and time in jail, the "Oppenheimer" star, who just won his first Academy Award, values his family tremendously. 

"It just gives me, honestly, something to attach my neurosis to that's positive," he said of his wife and children.