"Choosing to be together every day is incredibly romantic. I love marriage. I think it's a wonderful institution and it's the most important decision you make," she told Australia's Sunday Telegraph.
"Life is filled with highs and lows, and you have a best friend to share it with you. It's amazing. It's like winning the lottery, having a good partner."
Isla, who next stars in black comedy Bachelorette, also revealed that Sacha was once mistaken for a waiter - by her Bachelorette co-star Kirsten Dunst.
"We were at the Oscars, and it was the year that Sacha was up for an award for Borat, and Kirsten thought he was a waiter," she recalled. "He was by himself near the bar, because I was in the bathroom, and she goes up to him and says, 'Can you get me a glass of champagne?' Sacha was like 'OK', and he went off to find her one. I haven't let her live it down." Isla has two children with the quirky actor – she married the British comic in an intimate ceremony with just six guests in Paris in 2010, six years after they got engaged. They originally started dating in 2002, after meeting at a party.
The 36-year-old welcomed baby Olive in October 2007 before she and Sacha tied the knot. Their second daughter Elula Lottie Miriam arrived in August 2010, five months after they wed.
The couple had a long engagement, partly because their careers kept them busy, but also to give Isla time to convert to Sacha's religion - Judaism. Prior to the wedding Isla said: "I will definitely have a Jewish wedding just to be with Sacha. I would do anything – move into any religion – to be united in marriage with him. We have a future together, and religion comes second to love as far as we are concerned." She completed her conversion in early 2007, after studying for three years.
Isla has said in the past: "I'm not really comfortable talking about my private life and Sacha and I are probably very similar in that we hide our feelings behind humour."
The self-confessed eccentric once joked how the height difference between them – she is 5ft 2in while he is a statuesque 6ft 3in – made her look like "a circus freak".
For his part, her husband also shares her discomfort in talking about his personal life. The Borat creator usually only gives interviews in character, but in a rare interview speaking as himself he once admitted that: "Essentially I am a private person and to reconcile that with being famous is a hard thing to do."