Human beings are creatures of habit. Whether it's the ritual skim latte to start the day or the weekly devotion to "Will & Grace," people create routines that guarantee a series of small pleasures or comfort. Though routine can bring a sense of order to life in an increasingly chaotic world, it can be counterproductive when working out - following the same exercise regimen over and over not only gets boring, but can lead to exercise plateaus that can decrease your results.

"The human body is very good at adapting to the stresses it experiences," says Lisa Packheiser, a certified athletic trainer (A.C.T.) and a member of the Life Fitness Academy Training Network. "Performing the same activity repeatedly at the same level makes the body more efficient, which eventually results in lower caloric expenditure from the activity. In fact, research shows that by sticking to just one activity, the number of calories burned by exercisers may decrease as much as 25 percent."

For instance, if you normally exercise for 45 minutes four days a week on a treadmill with the same intensity and time for each workout, over time you will not benefit as much as you did when you began. Your body will become accustomed to the routine, and it can become increasingly difficult for you to meet your fitness goals. The repetitiveness also can be boring - even with music, TV or a magazine for distraction, the exercise might become mundane, which also can decrease the likelihood you'll continue working out.

Fitness professionals agree the best solution to dodge exercise plateaus and workout boredom is cross training. Cross training simply means mixing together a variety of exercise activities into a varied regimen.

Do you work out at a gym? Instead of 45 minutes on a treadmill each time, jump on a Lifecycle exercise bike for 30 minutes, then spend 15 minutes on a stairclimber. Swim one day and lift weights another. Health clubs with an extensive choice of group exercise classes make cross training a breeze; once a week try indoor cycling, step aerobics or kickboxing. Check out the newest classes emphasizing stretching and toning, such as Pilates or yoga.

Home exercisers also have options. Some treadmills can be raised for steep hill climbing one day, lowered for running flat the next. Or vary the intensity level - alternate going hard for five minutes and easy for five minutes. Premium equipment usually offers different exercise programs to help spice up your workout.

Check out other home fitness equipment, too - fitness equipment specialty shops, such as Omni Fitness, L.A. Gym Equipment and Fitness Resource, can help you choose a second piece that will complement the first. You may want to try to the hottest piece of equipment available today - elliptical machines that combine low-impact stairclimbing, skiing and cycling, like Life Fitness' X-Series Total-Body Cross-Trainers. Even participating in a recreational volleyball or softball league can add to a well-rounded, varied workout regimen.

Packheiser says clinical studies show most people plateau in their exercise programs somewhere between their sixth and eighth week. Exercisers should make sure they change their routines at least that often to maintain workout efficiency and prevent boredom. She recommends having at least two different activities that can be alternated daily or conducted within the same workout.

By taking the routine out of exercise, fitness fans can reap positive results and enjoyment from their workouts. They'll feel better, look better - and may even wish to add more variety to their lives. Skim latte? Next time, make it a cappuccino.