Chris Hemsworth has admitted his career put a strain on his marriage.

The 34-year-old actor married Elsa Pataky - with whom he has five-year-old daughter India, and three-year-old twin sons Sasha and Tristan - in 2010, and whilst he insists the pair are ''in love'', he admits it was difficult at the start as they ''didn't really see each other for a few years'' whilst Chris was conquering Hollywood.

He said: ''My wife and I fell in love, had kids, didn't really see each other for a few years, then fell back in love. In terms of work, [Elsa has] certainly given up more than I have. She'd like me to step back and be at home with the kids more, and of course, I want that too. But I feel like I'm at this crucial point in my career - I've just got to set up for longevity or I'll slip off.''

But the 'Thor' star says their relationship is as solid as ever, and reveals his secret to a long lasting marriage is making time for ''date night''.

He added: ''Once you have children, every instinct and every moment of your time is consumed by that. You've got nothing for each other. So, make sure you have date night even if it's once in a blue moon, because most of the time you're just too tired and you'd actually prefer to sleep.''

Chris has even thought about writing his wife love letters, as he believes he should tell her ''why or how'' he loves her as much as he does.

When asked by GQ Australia magazine if he's ever penned a romantic message to Elsa, Chris said: ''I don't, but maybe I should. There's no shortage of how much I tell her I love her. But I guess there's no detail in it, why or how.''