For Ozzy and Sharon Osbourne, it's perseverance. For Jimmy and Rosalynn Carter, it's maintaining separate work lives. For Doyle and Louise Brunson, having separate bank accounts helps.

A former first lady, a rock star who's been in and out of rehab, and a professional poker player can all offer considerable insight into the mysterious workings of marriage. After all, their wisdom is gleaned from decades of conjugal bliss.

The Marriage Ties That Bind

Ozzy and Sharon Osbourne in Beverly Hills last week. Michal Czerwonka for The Wall Street Journal

OK, maybe it wasn't always bliss. But each of them has stayed married—to the same person—for a very long time. And each considers his or her marriage to be happy, strong and mutually supportive.

In other words, they beat the odds.

It is often possible to understand why a marriage fails, as so many do. It is much more difficult, though, to elucidate why one succeeds. Why do some couples thrive, while others fizzle or flame out, despite their best intentions?

When I recently met former first lady Rosalynn Carter, who has been married to former president Jimmy Carter for 63 years, I couldn't resist asking how they made such a perfect union.

Mrs. Carter replied that she and her husband had gone through two periods in their marriage that were tough. "First, well, let me just say: Don't ever write a book with your husband," she said.

She went on to explain that the period after she and Mr. Carter left the White House and returned to their hometown of Plains, Ga., also put a strain on their relationship. Her husband felt adrift after failing to win re-election, she said. He would often interrupt her while she was at work in her home office, asking her to have a cup of coffee with him and chat.

"We learned that it was important to our marriage for each of us to always have our own work, our own projects," said Mrs. Carter, 82.

I asked my parents, who just celebrated their 46th wedding anniversary, why their marriage lasted so long. My dad said he had no idea. "Your mother did all the hard work," he admitted. Mom agreed, and divulged her marital secret: "forgiveness."

Happily married people believe they married their soul mates, and for good reason. Even marrying the right person gets you only part way. Ask the couples themselves, and they'll likely credit some combination of hard work and sheer blind luck.

James Cordova, a psychologist at Clark University, advises couples not to leave it to chance. You should assess your marriage at least once a year, he says. "Imagine going to the dentist only if your tooth actually hurt. At that point something has gone terribly wrong, and the odds of saving it go way down," says Dr. Cordova, author of "The Marriage Checkup." "Marriage is the same."

Of course, no one ever said that every day, or even every year, was going to be rosy. And there are plenty of long marriages that are unhappy. But there are some strategies that happily married couples say work:

Find the middle ground. "It's all give and take," says Marlene Critch, a retired hospital director in Tucson. She met her husband Bill on a blind date in 1959. He took her on a picnic with a thermos of gin and tonics; they married two months later.

Flash ahead 50 years. The Critches have raised two daughters in Seattle and weathered his severe heart condition. They swim together each morning, and he reads her children's books when she has trouble falling asleep at night.

Compromise, they say, got them through the good and bad times. Mr. Critch, 75, says he compromised by quitting the Air Force early in their marriage, because it bothered her that he was away from home so much. (Press him for more concessions, and he says, "Miso soup.")

Ms. Critch, 74, says she made her own compromise by agreeing to retire to Arizona, where her husband preferred the climate. (She wanted to stay in Seattle to be close to their daughters.)

"If each person can give 75 percent, you've got 150 percent," says Ms. Critch. Her husband agrees. "Many men would call that wussy," he says. "But I don't because I value her more than anything else in the world."

Similarly, Jan and Len Konkel, who have been married for 62 years, long ago made a pact to never argue over anything that wasn't very important, saving their battles for things like how to raise their three children. "Everything else is minor and can be settled in a discussion," says Ms. Konkel, 84.

Her husband agrees. "I say 'Yes ma'am' and 'No ma'am' a lot," says Mr. Konkel, 88.

Be funny. On the night in 1967 that Jackie and Ken Egan met at a dance club in Boston, he asked her for a kiss. She declined: "I don't know you," she told him. "And my kisses are like Lay's potato chips—you wouldn't be happy with just one."

The Egans, who live in Marshfield, Mass., and have four children, just celebrated their 40th wedding anniversary on Monday. Ms. Egan says laughter helps them deal with issues that would otherwise drive them nuts—such as Mr. Egan's fussy eating habits and forgetfulness about putting the toilet seat down. Or Ms. Egan's inability to let her husband finish a story without interrupting him, or her many knickknacks.

"You need to learn to find the humor in each other's annoying habits. It helps you keep the affection," says Ms. Egan, 69.

Keep (some) secrets. When poker legend Doyle Brunson met his wife Louise at a country-and-western club in Texas in 1961, he told her he gambled for a living. And she accepted him for who he is. "Love is the most important thing," says Louise Brunson, 78. "You have to love your spouse more than life itself."

The Brunsons, who live in Las Vegas, have stood by each other through some serious trials in their 47 years of marriage, including the death of a daughter and an armed robbery of their home, during which they were tied up at gunpoint.

"You have to go forward, you can't go back," says Mr. Brunson, 76. Even so, the Brunsons don't share everything. He doesn't discuss his business with her. "I have won and lost millions of dollars without her knowing," he says. Ms. Brunson says that's just fine with her. "I have my own bank account," she says.

Never, ever give up. This tip is really important, so pay attention. Sharon Osbourne says it is how she stayed with husband Ozzy for 28 years and counting.

And she's married to the Prince of Darkness. He bit the head off of a live bat, for God's sake. (Ditto a dove.)

He also spent years strung out on drugs and alcohol. Never mind the groupies and the near-fatal overdoses. This man set fire to his house, passed out on a freeway median, and once tried to strangle his wife.

Ms. Osbourne, for her part, tried to run him over with a car, smashing his gold records with a hammer and taking out a restraining order. "We became like a soap opera," says Ms. Osbourne, 57, who is her husband's manager.

And yet she stuck by her man. Why? Because she felt he was a good person when sober and that he would kick his addictions one day. And she still believes he is her soul mate. ("Twice recently we've had the same dream on the same night," she says.)

"I went into marriage thinking it was forever. So I was stubborn," says Ms. Osbourne who has three children with her husband.

Mr. Osbourne, who was married once before, finally did sober up "six or seven years" ago, he says, and is very glad his wife stuck it out. "You don't throw in the towel at the first sign of trouble," he says.

And so Mr. Osbourne has made a point of telling his wife he loved her every single day—no matter where he was in the world, no matter how drunk or high. "She sometimes said 'Drop dead' or 'F— off,'" he says. "But at least if you are arguing, you are talking. If you stop talking, it's time to call it a day."

Stay alive. My sister, a doctor, told me about one of her patients, a 92-year-old woman who showed up for her appointment with her husband, who is 94. They said they have been married for almost 70 years.

My sister, highly impressed, asked the couple the secret to their union's longevity. And they looked at each other for a long moment. Then the wife spoke: "Eh, neither of us died."

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