The divorce rate in the U.S. has been on a steady decline. New data reveal that the 2015 divorce rate dropped to the lowest overall rate in 40 years, according to the National Center for Family & Marriage Research at Bowling Green State University in Bowling Green, Ohio.

While no one knows what makes individual couples fight for their marriage and others to just give up, perhaps a fair number of happily married couples know how to “map” — or keep details about their spouse stored in their mind.

After asking your spouse a question, listen carefully to the details in their response. Don’t just hear the words, but also notice their facial expressions and emotional tone.

Dr. John Gottman, professor of psychology at the University of Washington in Seattle, has learned that the secret to love is in the details.

Gottman presented key findings from over 30 years of research in his best-selling book, “The Seven Principles for Making Marriage Work.” Many of his conclusions come from direct observation of married couples in his “love lab” — a set of apartments in which Gottman and his research team observed volunteer couples through one-way windows and video cameras.

Gottman studied newlyweds and found that 67 percent of couples saw a significant drop in marital satisfaction after becoming first-time parents. The other 33 percent remained at least as happy as they were before, but half of these experienced increased martial satisfaction.

The secret ingredient in the marriages of couples who thrived after becoming first-time parents is that they had what Gottman called detailed “love maps.” In his book, Gottman described a love map as the part of the brain in which spouses store all the relevant information they have gathered about each other. Relevant information includes things like details about their history, food preferences, hobbies, and sports interests.

Related: How to Support Those Who Marry Young

I love it when my wife remembers not to put ketchup on my hash browns. That’s the kind of detail that gets stored in a love map.

Couples don’t start their relationships with love maps; they have to create them over time. Married couples who do this — and update the information as their spouse’s world changes — set themselves up for a happy, lasting marriage.

My wife and I have been building our love maps for almost three decades. Here are my best tips for spouses who want to start creating theirs, or build on the information they have already:

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1.) Make a habit of asking questions of your spouse.
Sitting down together and reviewing each other’s childhood photo albums, asking about the photos and more, is a great way to learn about major life events in the other’s history. Doing this can also reveal other details, such as likes and dislikes and unfulfilled hopes and dreams. Other clues about your spouse’s interests can come from paying attention to what your spouse reads, what he or she watches on TV, and what grabs your spouse’s attention when you’re out together. Be curious about these clues; ask about them.

2.) Listen intently to your spouse.
After asking your significant other a question, listen carefully to the details of the response. Don’t just hear the words, but also notice facial expressions and emotional tone. Use this information to formulate follow-up questions.

3.) Use your discoveries to create special moments.
Use the information you gather about your spouse to create special moments. As you build this love map of your spouse in your brain, draw on that information for special occasions, such as Valentine’s Day, other holidays, anniversaries, and birthdays.

I bought a bouquet of cut roses for my wife on our first Valentine’s Day together. We were only dating then, and I expected her to be thrilled. She wasn’t.

“You don’t seem very excited,” I said.

I was surprised when she told me she didn’t like cut roses, because after a few days they wilt.

“What do you like?” I asked. She liked potted flowers, she said, because they lasted. So the next time I bought her flowers, it was a pot of living carnations. She liked that. After we married and had our first home with a yard, I bought her a rose bush for Valentine’s Day — she loved it! This is how the concept of love maps works.

Related: How to Build a Love That Lasts, No Matter What

You don’t have to wait for special days to show up on the calendar. You can also create special moments throughout the week, mining your “map” to let your spouse know you’ve listened and learned about the things that are important to him or her, and that those things are now important to you.

Jon Beaty, life coach and father of two, lives near Portland, Oregon. He’s the author of the book “If You’re Not Growing, You’re Dying: 7 Habits for Thriving in Your Faith, Relationships and Work.”