By Laura Snyder

It has to be one of the big five complaints of happily coupled-up guys: You want sex and she doesn't. It's sad, but true, that after those delirious early days of courtship, stress and obligations can cut even the lustiest girl's libido. But she still wants you...you just need to unlock her inner sex kitten. Here's the key:

Ask, Don't Beg

No offense, fellas, but it's little wonder your honey doesn't immediately strip off her clothes when you come to her begging like a spoiled child. First, stop pouting and tossing out accusations like "we never have sex." Then, like any good salesman, think of a way to ask for what you want that maximizes the chance that she'll say yes. Instead of it being all about you ("I want to have sex"), make sure it's about her ("You make me so hot").

Help Her Out

She says she's too tired to have sex, and she isn't kidding. Studies show that women who work outside the home devote more hours to childcare and household chores than their husbands do. While your ideal fantasy of her might include stilettos and sexy lingerie, she'll probably get a thrill picturing you with a dishtowel and some detergent. Share the chores, so you'll both have the time and energy for more fun pursuits.

Have It Her Way

Hey, if you want it so bad, then you should be willing to expend the energy to get her as aroused as you are. Every woman has some secret desire that makes her very hot, very fast. Figure out what it is - whether it's oral attention or acting out a particular fantasy - and she'll want you as much as you want her.

Stoke Your Competitive Spirit

Whether it's beefing up your biceps because one of your buddies did or pushing for a promotion to keep up with a corporate-ladder-climbing coworker, competition fires us up. Why not use that same flame to heat up your sex life? Get inspired by the latest surveys showing committed-but-carnal couples or by the steamy stories you hear from your still-passionate pals. Who knew keeping up with the Joneses could be so much fun?