Robert Wagner and Jill St. John's 36-year marriage has stood the test of time - here's their secret

Robert Wagner and Jill St. John are one of Hollywood's most enduring couples. The pair began dating in 1982 and have been going strong ever since.

In a recent interview, the Hart to Hart star shared the secret to their 36-year marriage. "Being interested in life and in your relationship," the 96-year-old told Entertainment Weekly. "I mean, I find Jill very interesting, a very interesting person. I think interest is important in a relationship."

Both actors had been married three times prior to striking up a romance. 

Shedding some light on the early days of their relationship, Jayne Smith, a friend of Jill's, told PEOPLE in 1982: "That was it. [Wagner] just started calling. They started dating and have been ever since. She’s really in love."

Robert and Jill's love story

Robert and Jill, 86, first crossed paths in 1959 when they were contract players at 20th Century Fox. They worked together on several occasions over the years, including in the 1967 movie Banning,  the TV movie, How I Spent My Summer Vacation, and the 1989 miniseries, Around the World in 80 Days

They reconnected at a dinner party in 1982 and tied the knot eight years later in a small private ceremony in the garden of Robert's home in Pacific Palisades, Los Angeles.

Robert's daughters Kate, Natasha and Courtney were all present, with Kate serving as maid of honour, and the other two as bridesmaids. 

Robert and Jill split their time between Los Angeles, California, and Aspen, Colorado for several years before moving to the latter full-time in 2007. 

In May, the couple celebrated their 36th wedding anniversary. Marking the special occasion on social media, Robert shared a sweet image of himself planting a kiss on his wife's cheek. He captioned the post: "36 years of love and laughter with my beautiful Jill. Happy Anniversary, my love."

Robert also paid tribute to his other half on her 86th birthday in August. "Wishing the happiest of birthdays to my beautiful wife Jill," he wrote alongside a photo of the pair posing in front of a scenic lake. "I'm so blessed to love you and to do life with you. Happy Birthday, beautiful

Robert and Jill's blended family

Robert is a proud father of three. He welcomed his eldest daughter, Kate, during his first marriage to Marion Marshall, and later had his daughter Courtney in 1974 with his late wife, Natalie Wood. He also adopted Natalie's daughter, Natasha, from her previous marriage to producer Richard Gregson.

Jill, who doesn't have any biological children, is a stepmother to all three.