For better, for worse, for richer, for poorer, what is it that makes a marriage last (and last)? To answer this age-old question, family sociologist Karl Pillemer, launched the largest in-depth survey of long-married couples ever conducted, interviewing 700 people who had been hitched an average of 43 years. Their sage advice is collected in his new book, 30 Lessons for Loving ($26, amazon.com).

Here, a few of our favorite practical relationship tips from husbands and wives who’ve discovered the true meaning of commitment.

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Start the day with a small kindness
“When you wake up in the morning, think, What can I do to make his or her day just a little happier? The idea is you need to turn toward each other and focus on the other person, even just for that five minutes when you first wake up.”
—Antoinette Watkins*, 81

Remember that being close doesn’t mean you’re the same
“You have to be able to try—and sometimes this is very, very difficult—you have to try to understand what the other person is thinking in any given situation. The main thing is that everybody—including your partner—has their own ideas about their world. Even though you’re in a very intimate relationship, the other person is still another person.”
—Reuben Elliot, 72

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Stop worrying about your wrinkles
“Somehow as you get older you kind of get blind to the infirmities that affect the other party. And you always see them the way they were. You don’t see aging. It’s a wonderful thing. I don’t know if the brain is wired for that, but that’s the way it is.”
—Alfredo Doyle, 77

Find your “fight number 17”
“This may sound like a flip thing, but it works for us. We came up with it at some point along the way: We call it jokingly ‘fight number 17.’ … It means we’ve had this one at least 16 times before. We’ve decided we don’t even bother to have it anymore. We see it coming and we just shut up and don’t even start with it. Because it’s not going to go anywhere. My theory is that in every marriage there is one of those issues.”
—Ralph Perkins

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Nurture the friendship
“I think it’s hard when you’re young and hot on one another to back off and say, ‘Do I like what is behind these hands and these body parts?’ But that is the piece that doesn’t wear out, that grows and deepens. The sexual aspect deepens, too, in its own way, but it becomes less important and the friendship becomes more important as the years go by. It will be challenged by kids and hardships and losses of parents and changing interests and patterns, but an abiding friendship is at the base of a solid marriage.”
—Lydia Wade, 73

Surround yourself with happy couples
“If you’re hanging around with negative people, find some positive people and hang around with them instead. You know, success imitates success. So if you see people who seem to have a very successful happy marriage, well, you hang around with those types of people. It does rub off. Avoid the ones with a defeatist attitude—get out of there before they drag you down.”
—Jeremy Bennett, 80

Repeat back to each other
“We realized early on that disagreements often came about when we weren’t really understanding where the other person was coming from. So I will say, ‘Are you saying….?’ Or ‘Do you mean…?’ Because sometimes we really are in the moment and we say things that we really don’t believe. So I always repeat back to him what I think he’s saying and then he’ll either say yes or he’ll say, ‘No, where’d you get that idea?’”
—Lucia Waters, 75

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Divvy up chores based on your strengths
“You just need to share at home…It needs to be cooperative. And here’s the way to do it: Whatever needs to be done, the person who can do it best is the one who should do it.”
—Dixie Becker, 84

Take breaks
“If conflict occurs, well, there is the Chinese saying, ‘Take a step back, and you can see the whole sky.’ Just step away, a little bit. Just step back and then you see other things.”
—Chen Xiu

Know that there’s always more to learn
“It seems to me that marriage is a process. You never get there; you’re always in process. It’s always more work than you can possibly imagine. In my case, it was worth it.”
—Samantha Jones, 80

This article originally appeared on Health.com.