You'll work harder than you ever imagined.

Early on, when people say, "Marriage takes work," you assume "work" means being patient when he forgets to put down the toilet seat. In your naivete, you think that you will struggle to accommodate some annoying habit, like persistent knuckle cracking or flatulence.

If only it were that easy. Human beings, you may have noticed, are not simple creatures. Your man has mysterious, unplumbed depths -- and from where he sits, you're pretty complicated, too. You have to learn each other the same way that you once learned earth science or world geography. And getting married doesn't mean you're done -- it just means you've advanced to graduate-level studies. That's because every time you think you've mastered the material, he'll change a bit. And so will you. As two people grow and evolve, the real work of marriage is finding a way to relate to and nurture each other in the process.

"It's like losing weight," says Andrea Harden, 45, of Buffalo, NY. "You want it to be a one-time deal. You lost it, now just live. But then you learn it's a lifestyle. That's marriage. The effort is a forever thing." So don't be too hard on yourself -- or him -- on those days when you feel like you're struggling through remedial math.