Warren Buffett may know more about smart investing than any other human on the planet, but he outdid himself when he openly shared what he calls the biggest decision of his life: marriage.

Well, not just marriage, but picking the right person to marry. As the billionaire told his shareholders at a 2009 Berkshire annual meeting:

Marry the right person. I'm serious about that. It will make more difference in your life. It will change your aspirations, all kinds of things.

Even research agrees that having the right life partner matters--to the point of increasing a partner's own salary, regardless of gender, by approximately $4,000 more per year. 

While Buffett's own marriage arrangement has been called "unconventional," one thing every marriage must become for partners to reap the benefits is sustainable.

7 things to do to make your marriage last

I've been married 10 years now and I can say with confidence that it takes a lot of hard work and commitment. To truly make it an effective partnership, both parties must have a desire to grow--grow as individuals and grow in the relationship.  

Here are seven ways you can keep your marriage happy over the long haul.

1. Seek objectivity during a conflict.

In social psychology professor Eli Finkel's new book, The All-or-Nothing Marriage: How the Best Marriages Workhe offers a number of crisis-avoiding strategies, including objectivity. He says partners should get perspective from a third party who sees things from the "outside." Bringing that objectivity helps to simmer down escalating arguments.

2. Get enough sleep.

In The Happy Couple, author Barton Goldsmith cites a study from the University of California, Berkeley, that looked at the sleep habits of more than 100 couples. Couples who reported poor sleep were much more likely to argue with each other.

3. Show small acts of kindness.

Something as simple as a shoulder rub after an exhausting day of work or making a cup of coffee for your partner before he or she wakes up is a relationship booster. Terri Orbuch, a marriage researcher and author of 5 Simple Steps to Take Your Marriage From Good to Great, studied 373 couples for more than 28 years and found that frequent small acts of kindness are a predictor of happiness in a relationship. 

4. Be attractive to your partner.

The attraction I speak of goes beyond the physical and into the emotional. When one partner connects with the other at his or her best, sparks fly. That may mean openly displaying one's high esteem and zest for life, a passion for a particular interest or cause, or that intrinsic drive expressed through a career you love. As you embody your attractiveness and live life to the fullest, your partner will reflect that same passion. That's attractive!

5. Create space for spontaneity to happen.

When you're mega-busy with life's many professional and personal commitments, marriages can stop being interesting. In one study, researchers found that couples who reported boredom during their seventh year of marriage were significantly less satisfied with their relationships nine years later. Solution? Keep things spicy and avoid "same old, same old." Experts recommend trying new things like a dance class or enjoying a random lunch picnic on a workday. The point is to create space in your life for spontaneity and creativity to happen. That opens up all kinds of possibilities to bring the romance back.

6. Double date.

In The All-or-Nothing MarriageFinkel found evidence that when couples openly share their relationships with others on double dates, romance is rekindled. "In short, socializing with our spouse and other people can stoke the romantic fire in our marriage, but only if the socializing is fun and intimate," writes Finkel.

7. Exercise together.

A recent study published in Mayo Clinic Proceedings finds that the social interaction involved in partner and team sports may add more years to your life than solo exercise. Whatever activity you choose together, doing so is better for longevity than standard solo activities like jogging or cycling. "If you're interested in exercising for health and longevity and well-being, perhaps the most important feature of your exercise regimen is that it should involve a playdate," study co-author James O'Keefe told Time

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