Regularly change your routine. Many people fall into a fitness rut, doing exactly the same activities in the same way at the same time, week after week. While regularity and consistency can be useful, lack of variation often leads to boredom. 

Evaluate your current routine to figure out what bores you. A new twist on your favorite activity -- such as using free weights instead of weight machines, or kickboxing instead of step aerobics -- may be enough to breathe fresh air into a stale routine. If you've been jogging, biking or swimming indoors, try doing the same thing outside. Consider changing the order of your weightlifting routine.

If you know you're the type of person who's easily bored, plan to make small changes to your routine every month. Any change can be enough to inject some new challenge. Avoid sudden increases in exercise intensity, which can put you at risk of injury.

Explore new activities. If tweaking your current routine doesn't do the trick, consider an entirely new activity. If you've always exercised on your own, join in on a team sport, such as basketball, volleyball or soccer, or enlist a regular tennis partner. Try out activities that you've never even thought of doing before. The possibilities may include archery, rock climbing, jumping rope, kayaking, canoeing, badminton, in-line skating, karate, rowing, dancing, yoga, tai chi, and cross-country skiing. Have fun!

Add variety by cross-training. Cross-training, or alternating between different activities, is not just for elite athletes. It's a good way for anyone to ward off the exercise blahs. It also improves your overall fitness and reduces your chance of injury from overusing a specific muscle or joint. You can alternate activities -- such as walking, swimming, weight training and bicycling -- on different days of the week or even in a single workout. Ideally, your overall program will include aerobic exercise, strength training and flexibility exercises.

Work out with a friend or group. Socialize while you exercise. You and your companions can encourage one another to keep going. Get a group together for a weekend hike and picnic, or have a friend join you for an evening walk. Consider setting exercise dates once or twice a week with someone who's equally committed to physical activity. You're less likely to skip a workout if someone else is counting on you being there.
Join a sport club or fitness class. Just about every sport or activity has a club. Ask about organized workouts, fun runs and group bike rides or hikes. Health clubs, community centers, parks, schools and gyms offer a variety of fitness classes.

Listen to music. Upbeat music can rev you up and may increase your pace. One study found that listening to music during exercise made the workout seem easier. It can also make the time pass more quickly.

Challenge yourself. It's great to exercise simply to stay in shape, but you can make your daily workouts more meaningful and exciting by setting a goal that exceeds your current fitness level. For example, if you like to hike, plan to trek through your favorite national park. Consider training for a 10-kilometer (10K) race or triathlon.

Try interval training. Interval training involves alternating short bursts of high-intensity exercise with active recovery -- a less intense form of the activity. In a 30-minute workout, for example, you might run for three or four minutes, jog or walk for five, then run again for three or four, and so on. Start by incorporating short bursts of speed into your regular workouts -- for example, running to the next tree or sprinting one lap in the pool.

Learn more about technique. It's easy to fall into a set way of doing your activity. One way to challenge yourself is to learn more about training and technique, as well as alternate approaches to your workout. For example, there are many different ways to train with weights. Explore a new technique.

Get an exercise gadget. Exercise devices such as heart rate monitors and pedometers aren't necessary, but they can add fun and challenge to your routine. Find out what new training equipment is available for your activity.

Take an occasional break. A day off from your routine every now and then can recharge your batteries. Sometimes you really do need time off.