Dax Shepard admits his marriage takes a ''tremendous amount'' of work and therapy.

The 42-year-old actor worries people think he and Kristen Bell - who he wed in 2013 - have an idyllic union when it actually takes a lot of effort and commitment to make their relationship last.

He told Us Weekly magazine: ''We don't believe in The One. We don't believe in the fairytale. We don't believe that you can meet someone and you have a perfectly matching personalities.

''We are opposites and it has taken a tremendous amount of work and therapy for us to co-exist.

''My only fear is that people see us and think, 'Oh, I just need to find my Kristen Bell.' That's not true. You'll find your Kristen Bell but guess what, now the work starts.

''[Relationships] are labour intensive. If you want them to last they are labour intensive.''

The 'Parenthood' actor - who has Delta, two, and Lincoln, four, with Kristen - recently admitted he likes to do romantic things for his wife.

Asked about the most romantic thing he has done for Kristen, he said: ''We got into this really crazy one-upmanship of - so she was doing a movie in Alaska and I was shooting 'Parenthood' and I couldn't go and she was going away for a long time. But then my schedule changed and I didn't tell her, so I got the seat next to her on the airplane and then I sweet-talked the gate representative to let me on the plane early.

''So when she went to sit down, I was in her seat reading a newspaper and she kept going, 'Excuse me, sir. Excuse me, sir. I think you're in my seat.' And then she noticed those hands look familiar and then she started bawling when she saw that I was on the flight. And then so she did it to me on the way back.''