Streep, Jones & Carell Spark 'Hope' at Premiere

Meryl Streep, Tommy Lee Jones and Steve Carell were all smiles at the world premiere of their new romantic comedy Hope Springs in New York Monday night, and ET was there! So what advice do the stars have to keep the spark alive in relationships?

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"Darling, if I knew that, I'd write the book," said Streep with a smile, while Jones cracked, "I'm the worst person to ask for advice on relationships."

"We're still together, but we're not saying it's exciting," joked Carell with his wife by his side – who coincidentally were celebrating their 17th anniversary. "Our needs are very limited."

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In theaters Friday, Hope Springs stars Streep and Jones as Kay and Arnold, a devoted couple who have lost the spark in their marriage after decades together. Hoping to spice things up and reconnect with her husband, Kay seeks out a renowned couple's specialist (played by Carell) in the small town of Great Hope Springs for a week of marriage therapy. Can they re-ignite the spark that caused them to fall for each other in the first place?

Hope Springs was directed by David Frankel (Marley and Me, The Devil Wears Prada).