Jimmy Carter and Rosalynn Carter celebrated their 75th wedding anniversary last week, the longest marriage of any American president. At 96 and 93 respectively, they're still very much in love, and they offered some great advice for the rest of us who want our unions to truly last a lifetime.

1. Make the other person your partner in everything you do.

This may be tough advice to follow if you're an entrepreneur or business owner accustomed to relying on yourself and making your own decisions. But, the Carters would tell you, if you want to be in a true partnership with another person, that means sharing everything--including your career choices, which will inevitably affect your partner or spouse.

Jimmy told The New York Times that one of his biggest regrets was that early in their marriage, he made big decisions without consulting Rosalynn. For example, after his father died, he decided to leave the Navy and return to their hometown of Plains, Georgia, and take over the family peanut business.

That infuriated Rosalynn because, as a wife and mother in the early 1950s, she'd enjoyed the independence of living far away from her mother and mother-in-law. Returning to Plains, "I was going to have to come back to them," she said. Later, Jimmy learned to include her in everything, including his campaign plans and even cabinet meetings. 

2. Never go to bed angry.  

The Carters say following this rule is one big secret to a happy marriage. Although my husband and I, at 21 years of marriage, are amateurs by comparison, it's a rule that's worked for us, too. 

But it doesn't mean you shouldn't fight. There's a small audience of Inc.com readers who receive a daily text from me with a self-care or motivational micro-challenge or idea. Often they text me back and we wind up in an ongoing conversation. (Interested in joining? You can learn more here.) Sometimes they text me about their relationships, and things always seem to get better when they and their partners talk through whatever is bothering them, even if those are difficult or acrimonious conversations.

A wise couples therapist once told me that for a relationship to work, there has to be room for each person in it to get very angry on occasion. But when those occasions arise, it's also important to talk things out and try to reach some kind of understanding, even if you're just agreeing to disagree for now. Coming to that understanding before you fall asleep means you won't be stewing in your angry feelings all night. You can look at the problem with fresh eyes, and in a calmer state, come morning.

3. Make sure to enjoy each other's company.

For the Carters, that meant finding shared interests over the years, including fly-fishing, skiing, and bird-watching. For me and my husband, travel tops the list of beloved shared activities. But even if you're just taking a walk around the neighborhood or going out for breakfast, finding ways to enjoy being together--sharing thoughts, ideas, memories, or a companionable silence--can make all the difference.

This is such a no-brainer, and yet in the crush of life and work, it can be easy to forget. If you enjoy being with your partner, you'll be more motivated to make the relationship work, and so will he or she. That's important because with all relationships, even really happy ones, it takes work to keep them alive.

But if you're with the right person, doing that work is well worth the effort. Jimmy was elected president and won the Nobel Peace Prize, but still told the Times that marrying Rosalynn was "the best thing that ever happened to me." And, he said, "I love her more now than I did to begin with--which is saying a lot, because I loved her a lot."