A few tweaks can pump up your exercise routine

You've emptied the garage, redecorated the bedroom and turned over your closet — with spring weather comes spring cleaning, of course. But what about your exercise routine? Like everything else in life, workouts start to feel stale if you do the same activity, day in and day out.

"People associate a new fitness routine with New Year's resolutions, but spring is a great chance to change up your workout," says Barbara Bushman, professor in the kinesiology department at Missouri State University and editor of the American College of Sports Medicine's Complete Guide to Fitness and Health.

In fact, mixing up your exercise program is key to making fitness a life-long habit. A study by exercise scientists at the University of Florida found that when people changed their routine every two weeks, they were more likely to continue exercising over the course of two months compared to those who followed the same routine. "I don't care how disciplined you are, when exercise becomes boring, you stop doing it — that's just human nature," says Jimmy Minardi, a personal trainer and founder of Minardi Training.

On a physiological level, the problem is that your body adapts to a specific routine over time, teaching itself to perform movements more efficiently. This may sound like a good thing, but it means you are burning fewer calories and activating fewer muscles, which makes losing weight and gaining fitness harder.

"Every time you try a new activity, you challenge different parts of your body, and that makes you fitter overall," says Minardi. Looking to give your routine a spring makeover? Start with these easy steps.

• Change your location. Sometimes, all it takes to breathe new life into a familiar routine is to do it someplace else. "If you usually walk on the treadmill, take it outside," says Bushman. "If you have a regular jogging route, try a new side street." Raise the challenge one notch higher by getting off the concrete and hitting the trails. "Trails require an additional level of focus and coordination to find your balance and negotiate unfamiliar terrain," says Minardi. No woodsy paths in your area? Make use of the steps at a local sports stadium, or walk up and down the stairs in your apartment building.

• Vary your intensity. You'll burn more calories by switching gears on your bike to add resistance for one minute, then switching back to an easier setting for the next. If you walk three or more days a week, try jogging. How to do it: Start by walking for five minutes, then adding two minutes of easy jogging, followed by another five minutes of walking, and so on until you reach 30 minutes. Each week, add another minute to your jogging segments, until you reach two 10-minute segments of jogging with five-minute walking breaks, then start subtracting walking minutes until eventually you can jog the full 30 minutes.

• Know your limits. People are more likely to get frustrated and give up when they set pie-in-the-sky goals, says Bushman. "Start by realistically assessing where you are right now, not where you'd like to be, and base your routine off that," she says. Can you walk at a brisk pace for 10 minutes? Try adding five more minutes, not 15. Do you use five-pound weights? Raise the bar to 7 or 8 pounds, not 10.

• Mix in strength moves. You don't need a ton of equipment to build muscle. "Machines quickly become mundane," says Minardi. "Meanwhile, games of volleyball or tennis are fun, and they help you build muscles in your upper body when you swing at the ball." Another option: Walk to the local park, then stop and do push ups, sit ups, pull ups (if there is a jungle gym) and lunges on the grass. Do 10 of each move, then switch; repeat the whole cycle three times. These exercises require minimal space and can be done at home as well.

• Reverse the order. If you usually do cardio (biking, walking, swimming) followed by toning (sit ups, push ups, etc), consider reversing the sequence of exercises. If you follow a specific weight machine circuit at your gym, do it backwards. Studies show that simply changing the order in which your body performs tasks is enough to stimulate new muscle growth.

• Explore new options. If you adore the stationary bike, you aren't alone: The low-impact nature makes this machine a favorite for people of all ages and fitness levels. But too much low impact may not be ideal. "Your greatest ally in fitness is bearing your own weight," says Minardi. "We are a sedentary culture — we sit at work, in our cars, in front of the TV — so any time you stand, walk or run, that weight-bearing activity does a lot to counter that sedentary life." (In fact, recent research indicates that habitual sitting can lead to higher mortality rates.)

Five Rules For Starting Your Spring Routine

Don't be intimidated by a new challenge.

1. Choose your goal. Research shows that specific goals keep you focused better than vague ones. Whether you want to lose 10 pounds or run a 5k, write it down on a piece of paper and post it somewhere you can see often.

2. Break it down. If you want to run a 5k, make a weekly plan for how many days you will run and how many miles you will complete. If the race is in four weeks, create a month-long plan that you will follow. Seeing your big goal sliced into bite-size pieces makes sticking with it much easier.

3. Pace yourself. Any time you change activities, you are calling upon new muscles to perform new actions. Give your body time to adjust by doing your familiar routine one day, and your new activity the next.

4. Find a partner. Sign up for your first class (yoga, Spin, TRX) with a friend. Initially, you will feel more relaxed in your new surroundings; over time, a little friendly competition will help you test your limits.

5. Make it fun. Exercise should bring an element of joy to your daily life. Listen to upbeat music; see how many sit ups you can do in 60 seconds; challenge yourself to bike just one more hill; reward yourself with a relaxing bath. "Don't take exercise too seriously," says Minardi. 'You just need to go out and play."