Picking an exercise video can be like an eenie-meenie-minie- mo game between doors on Let's Make a Deal: You never know if you'll end up with a nifty prize or a horrible joke.

Yet a well-done exercise video can provide just the motivation you might need to move a little bit. Not only are you saved from displaying every curve and bulge from the throngs at a health club, but you can also avoid the throng itself. You can also pick the type and level of exercise that's exactly right, and you can do it when it's exactly convenient. Plus, exercise videos can offer an incredible selection of specialty routines -- from boxing to country-line dancing -- you'll never see on a regular club schedule.

OK, OK, some of the selections are pretty outlandish (Tappercize? I mean, who has a tap floor in front of the TV?). Some are put together by today's stars riding on a wave of popularity (rapper Marky Mark, model Cindy Crawford, even cover- boy hunkster Fabio). Despite questionable products, many tapes are sane, effective, perhaps even fun ways to infuse your life and living room with a little exercise.

Deciding which little box to pick is the hard part. You can't always believe the cover hype, flashy photography and Madison-Avenue exercise descriptions, or put your trust in a well-placed chin mole or a buff bod. And, well, Hollywood production styles might make viewing more pleasant, but an instructor and routine that won't land you in the hospital are your No. 1 considerations.

Don't take any ratings as the be-all and end-all. A type of music, routine or personality one person likes might make you bounce higher or screech louder than Richard Simmons.

• Try a tape before buying, if possible. Rent exercise tapes at video stores, or borrow from a friend. Check out reviews of workout programs. Here a review of 21 Day Fix

• Make sure a store or catalog guarantees satisfaction.

• Look for instructor certification. Although not a water- proof guarantee, it could mean more knowledgeable instruction and attention to safety. [Three main certifying bodies are the American College of Sports Medicine (ACSM), the American Council on Exercise (ACE), and the Aerobics & Fitness Association of America(AFAA).]

• Try to be honest and decide if this is a fad workout or one you'll be able to live with.

• To keep boredom from setting in, build an exercise video library with a variety of different tapes that you can alternate based on your mood and time constraints.

Your small screen and living room could turn into the best of all health clubs.