Even skiers, winter campers and ice climbers have to admit this: winter has days that are just plain nasty. Ezra Pound said it:

Winter is icumen in,
Lhude sing Goddamm,
Raineth drop and staineth slop,
And how the wind doth ramm!
Sing: Goddamm.
Skiddeth bus and sloppeth us,
An ague hath my ham.

We may escape the ague, the exotic flu and the familiar head-clogging cold, but a more insidious winter threat is the difficulty of getting exercise on some days—and that kind of day can turn into a week.

Exercise is badly needed in winter, when cold makes hearty food look better that it does in the salad-bejeweled summer, and the lack of light is doing a number on our moods.

An economy like this year's, which creates a scarcity of money for skiing and even gym memberships, makes the problem tougher than usual. When rain makes the snow refreeze and it's worth your life to take a step outside your back door even with Yak Trax, it's pretty hard to get exercise.

How do you do it without spending hundreds of dollars? Here are a few suggestions about how to get exercise when we're closed into our houses and apartments and cabin fever lurks in the corners.

One possibility: instead of joining the health club this season, buy an exercise bike. They can be had (especially used ones) for two hundred dollars or less and stored even in a small apartment. That saves you not only the difference between the bike and the club membership, but the cost of gas to travel to the club and back. With the bike you can double up, watching your favorite TV programs while burning off calories and building strength. An exercise ball is good for days like this, too, as are weights if you have them and the proper environment in which to use them.

Here's a suggestion that may make you chuckle, but you'll be laughing on the other side of your mouth as you see your fitness improve. Invest $1.95 (or up to $20 if you want a deluxe version) in something you may not have used since age 12: a jump rope.

Jumping rope is a superb exercise that helps balance and coordination as well as working out arm and leg muscles. As a weight-bearing exercise, it has the endorsement of many experts, including some connected with the National Institutes of Health, whose Institute of Arthritis and Musculoskeletal and Skin Diseases has listed it as an activity that can help ward off bone loss in postmenopausal women.

Like other kinds of aerobic exercise, jumping rope can be done to music. If you have some initial difficulty with it, start in very slowly. But as long as you're healthy and reasonably fit, finding that you can't do it like you could when you were a child is all the more reason to keep going until you can jump comfortably. Use a rope that has some weight rather than a super-light vinyl type, stand erect, and jump lightly on the balls of your feet. Don't overdo it.

Remember the calisthenics you learned in school or in the armed services—the ones that get you stretching, touching your toes, jumping (like jumping jacks) and running in place, and the floor-based types like pushups? Those help get out the kinks that have been worked into your system by a desk job. They can combine with jumping rope as you alternate exercises to keep from repeating any of them until you're bored.

Jumping rope is also something you can use to spread fun and physical activity around if you're weathering a blizzard in your house with children, and so is dancing. Some people put on their favorite music, or music chosen by the kids, and dance up a spree in the house. Get everybody moving to a crazy-fast klezmer beat (or rock or polka) and you may be surprised at how much physical exuberance can be worked up indoors on a gloomy winter day.

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On the electronic side, there are workout videos you can use alone, with children or with a partner. You may be able to borrow them free at a library, or you may find them online. And you can ramp this concept up a giant step by checking out fitness software, or signing up with an online gym that offers programs you can access at your own convenience.

To check out a couple of models of this type of program, start by studying the offerings of Virtual Gym TV, a British program that allows viewers to sign up for exercise in a breathtaking variety of modes: pre- and post-natal yoga, "Abs Blast," "Legs, Bums and Tums," "Spinergy," "Kick Fit," "BootCamp" "Strength and Tone" and many, many more. They can "meet" (virtually, of course) their instructors and read fitness-related news ("Don't let the Christmas party spoil your fitness;" "Regular exercise can cut chance of developing breast cancer.").

Then point your browser to www.slimtree.com's Broadband Gym, which also offers a full menu of exercises—from yoga to martial arts and weight training—and a chance to share tips about your favorite workouts, track your weight and body mass index, and trade recipes.

Slimtree offers the chance to transfer its programs—for a nominal fee—to your hard drive, cell phone or personal digital assistant (PDA) for 30 days, after which they disappear. During their month of life, however, you can use them while you're traveling or otherwise disconnected from broadband.

Part of the attraction of these programs, of course, is not only that you get structure and a trainer—sometimes quite a respectably credentialed one—but that their interactive components add a social level to the business of getting exercise, the virtual equivalent of hanging with the folks at your local health club.

Where there's a will, there's a way is an old saw that's aptly applied to the problem of getting exercise on days when it's tough to venture outside. But whether you want to go low-tech with a jump rope or high-tech with an online gym, the point is to hit on something you enjoy. In the best-case scenario, exercise won't just be like a dose of castor oil—something you grin and bear as you dutifully burn off calories. You'll know you found the right solution if you find yourself turning to it again, even when better weather moves in and gives you more choice.