Celebrity couples aren't coy about why their relationships and marriages are so successful, working hard at it over the years, and have shared thoughts and advice on their relationships in interviews. Here are our favourite quotes

Celebrities speak out on the secret to long-lasting love

Andy Murray and Kim Sears (together since 2005, married since April 2015)

Beyonce and Jay-Z (married since 2008)

Iman and David Bowie (married since 1992 until his death in 2016)

Michelle Pfeiffer and David E. Kelley (married since 1993)

Ellen DeGeneres and Portia de Rossi (together since 2001)

Kate Middleton and Prince William (met in 2001, married since 2011)

Nicole Kidman and Keith Urban (married since 2006)

Sarah Jessica Parker and Matthew Broderick (married since 1997)

Angelina Jolie and Brad Pitt (together since 2005)

Alyson Hannigan and Alexis Denisof (married since 2003)

Katharine Hepburn and Spencer Tracy (together for 26 years until his death in 1967)

Julia Roberts and Danny Moder (married since 2002)

David and Victoria Beckham (married since 1999)

Vivienne Westwood and Andreas Kronthaler (married since 1992)

Tom Hanks and Rita Wilson (married since 1988)

Will Smith and Jada Pinkett Smith (married since 1997)

Helen Mirren and Taylor Hackford (togther since 1986)

Lena Dunham and Jack Antonoff (together since 2012)

Andy Murray offers a tip for newlyweds...