You're going to have to trust me on this one: if you can get your wife or girlfriend to start exercising, if she's not of course, you will have a lioness in the bedroom. Not only will her libido light up, but her strength and endurance as well. In other words, you better be ready - you might get hurt, Big Boy!
Now why do I say that you'll have to trust me on this one? Because I cannot find a study to support that statement, but I do know it works. And I've read it on many sites as well: exercise improves libido, decreases PMS and many other wondeful things for the fairer sex. It also does all the same wonders that it does for guys that I have already documented in my Exercise link. Again, females are different that males - oo la la! - but the foundations of their libido is similar. Almost always, what boosts your libido will also boost hers.
NOTE: One of the not-so-well-known reasons that exercise may boost libido for women is that it affects their body self-image so significantly. It's undoubtedly is the same with guys: if you don't feel good about yourself, your libido and bedroom performance can fade quickly. For example, the womens magazine, Self, recently found that 71% of women who were happy with their looks worked out at least three times per week.  By the way, body self-image may also be tied into happiness: 61% of happy women say their body is 'just right' as well. 
So the question of a lot of guys, who already know the Power of Exercise, are asking is:
"How do I get my spouse exercising?"
That can be a tough question, admittedly, because many women were never in sports or their families didn't take care of themselves or they feel overwhelmed with work and kids or they're the "ultra-feminine" type or any number of other things. Never fear, though, because you can lure almost all females into some basic exercising through one of the following exercise methodologies that I list below.
An important point is that hopefully you've been modelling the fantastic things that exercise does for you. With your spouse or girlfriend, or anyone you are close to for that matter, nothing speaks quite as loud as pure example. People admire someone who is disciplined and who gets results and, if you haven't already, use your own life to lay the foundation.
Some females don't want to exercise, but they do want to lose weight and realize how it is all but impossible to lose weight without moving one's booty at the same time. Again, in your sweet and gentle way, you can occasionally bring up the advantages of Exercise and good, clean livin'.
Remember, guys: this will be well worth your effort. Of course, the important thing is that she'll be healthier. Hopefully, you guys are in it for the long haul and, of course, exercise is probably the #1 thing you can do to improve her health. However, also keep in mind that exercise will likely decrease her PMS symptoms, improve her general mood, and boost her self-image as she loses weight and gains muscle. (We all know self-image is an all-important bedroom concept for both males and females.) And, yes, you will find that her libido will skyrocket as well.
Here are some great ideas that should get her moving if she's not already:
1. Yoga Classes. Many ignorant guys have said, "Yoga? That ain't exercise!" Then the dull fellow tried one of the simpler moves and cried like a little girl. Just one standard Yoga move will leave most guys quivering in pain and begging for mercy. Seriously, most yoga instructors are lean, muscular and emphasize a healthy lifestyle, all of which will benefits your wife's libido. CAUTION: Some yoga instructors lead students down a path of "overstretching" and injury. Watch out for those "down dogs"!
2. Pole Dancing. No, I'm not asking you to send your wife or girlfriend down a new career path. I'm talking about her learning to pole dance either in an exercise class or in the privacy of your own home. This ain't for every girl, but a lot of females find this a fine form of exercise that is a complete strength and aerobic workout. You'll have to check locally, but in a decent-sized city, there are usually pole dance classes that are both legitimate and popular. Alternatively, you can install a pole at home either permanently or non-fixed. Of course, with the non-fixed variety, your woman can't do those Cirque du Soleil moves that you were hoping for. Finally, if the female in your life does let you watch her pole dance, be sure to put your tongue back in your mouth!
2. Gym Classes. You may enjoy weights and the treadmill, but have you noticed there's more guys out on the floor than females. The reason is simple: most of the women are in taking classes. These classes often emphasize things like dance and group participation that us muscle-bound hunks avoid like the swine flu. When I play basketball, I barely notice that I am working and sweating like a pig because I'm having so much fun. Well, these classes are the same thing for a good percentage of females out there. And, again, don't give me a "that ain't no exercise" excuse: most of these classes are brutal and will leave you whimpering. Break out the card and sign her up!
3. Dance. If you enjoy dancing - I've seen pictures of people who do - sign the two of you up for dance classes. Most dance is darn good exercise and will achieve the goal of blood flow and circulation. Plus, a huge block of women out there enjoy dancing (assuming you don't remove a toe nail off of her as I once did). Remember: not only will the exercise boost her libido, but you may find that you score a few additional points as well!
4. Walking. Assuming a walk in your neighborhood doesn't require packing heat or a Marine escort, there is no better way to burn calories. Walking is steady and enjoyable. In fact, why don't you guys walk together sometimes. A romantic walk coupled with your witty humor and thought-provoking insights could very well score even more points than #3.
5. Exercise Videos. Many women love this form of exercise. They can buy a video of kickboxing, aerobics, dance, yoga or whatever they want and sweat and breathe heavy in the privacy of their own bedroom (where that sort of thing ought to be done).
6. Boot Camps. Boot camps are becoming increasingly popular, where women enroll in a gym or fitness program's one or two hour program several days per week. Turning fat to muscle and burning lots of calories are usually the big goals. Because these are done in a group and with good intensity, results can be very good.
7. Zumba. Zumba is becoming very popular. It is often taught in gyms and other fitness locations. This is quite popular with some females as it is high energy and dance oriented. Calories for many women are burned off without even noticing. It emphasized latin dancing and is designed to be relatively easy to learn and follow. A Google search can pull up a mountain of information including classes in your area.
8. The Dailey Method. The Dailey Method recently went national.and is quite popular as it combines ballet movements with core conditioning and stretching.
9. Trainer. For some people, a personal trainer is a huge asset, supplying a much needed dose of accountability and expertise. This is especially true for females with definite weight loss and other goals but limited time to research the best way to do it. Plus, just having to show up every few days and explain to someone what you have and haven't done is a big motivator.
10. Cardio Tennis. This is a natural for both women and men. Tennis is one of those pleasurable sports where you don't even notice you are getting a fantastic workout because it is so enjoyable. Even if you haven't played, get yourself a few lessons and start playing. Most decent-sized cities (in the U.S. at least) have organized Cardio Tennis. You can expect a good dose of fat-burning, growth-hormone-producing intensity along with the standard workout paces. See the Cardio Tennis Site for locations and details.
11. Weight Training. Many women really enjoy weight training once they learn that muscle burns fat. Women also greatly other women with "toned arms and shoulders" and want the same. Females also have several advantages over us testosterone-laden males, including a shorter recovery time. Sroll down to this link on Female Strength and Weight Training for some interesting details. And this can be a nice way for you and her to do something mutually beneficial together, eh Pierre?
Again, if you can just get her started, everything will take care of itself. She'll start to get that endorphin high from the workouts. She'll look better, feel better, lose weight and many other things that will be highly appealing to women. In fact, after she drops a dress size, she'll be hooked.
Some of these can involve time and money. Yes, you may have to watch the kids for her while she heads out to burn some calories and, yes, you may need to forego that compressor for a month or two so she can get a gym membership. It's well worth it, though, and will pay off in almost every aspect of both her life and yours - yes, even in the sheets.
1) Self, 2/2010, p. 102.