William H. Macy says you have to "work on passion" in a relationship.

The actor shared his top tips for a happy marriage and admitted that sometimes you have to act to please your partner.

The star has been married to Desperate Housewives actress Felicity Huffman for 15 years and knows that treating your partner lovingly pays off.

"Just act like you love her more than anybody you've ever seen in your life, and you'll get it back in spades. Just pretend. You have to pretend. Make it up, just make it up!" he told TV & Web series In The Mixx.

"Marriage is really hot and ooey-gooey for about a year or two, and then the rest of it is a relationship, which you got to work on. You can have passion, but you've got to work on it."

William was speaking at the Sundance Film Festival, where he is promoting his movie The Surrogate.

The 61-year-old said that every couple has to find out what works for them.

He explained that you have to decide to make an effort and then work on it.

"Role play. Do whatever you need," he said. "The point is, you've got to set your sights. You've got to say, 'Do we want to make this hot? Or do we not?' And if you do, then do it! Don't give yourself excuses."