Expensive gyms and fitness centers always do a booming business in January, as people resolve to get fit. But those who lack the money or time to go to a gym don't have to to stay on the couch.

Colleen Greene, wellness coordinator with MFit, the University of Michigan Health System's health promotion division, says you don't have to invest a lot of money in a gym membership or equipment to develop a successful and sustainable fitness regimen.

Her first piece of advice is to make a resolution to become healthier overall, instead of only focusing on dropping pounds.

"Traditionally the number one New Year's resolution is to lose weight, but it should not necessarily only be that. It should be improving your fitness, and losing weight may be part of that," Greene said.

Greene says by purchasing the right equipment, adding creativity to your workouts, and keeping your motivation up, you can start an exercise program around the house that will last. She offers the following tips:

1. Get a fitness assessment. An assessment done by a personal trainer will help you decide what your goals should be. For example, it will show if you need flexibility work or if instead you should focus on increasing your cardiovascular capacity. This will provide a starting point for fitness planning.

Also, be sure to check with your doctor to ensure that your new routine will be the best and safest one for your individual needs.

2. Purchase equipment that is right for you. Don't get something that is just going to end up being a coat hanger, Greene advises. "You want to look at what is exciting to you, what you will do and what to focus on once your assessment has been done," she said.

"Do you need the cardiovascular exercise? Buy a cardiovascular machine. Do you need some strength training? Purchase a Dyna-band or small hand weights. It depends on what sort of equipment you need and what sort of equipment you are going to use."

3. Be creative. Do you have a can of soup? Then you've got yourself a dumbbell. Using the resources around you not only mixes up your routine, but it saves you some money too. You can even use your own body weight to do various resistance exercises that help to increase your strength, Greene said.

4. Embrace the outdoors. There are many winter activities that people can do outside that can be fun and safe. Snowshoeing, cross country skiing and even going outdoors to play with your children are great ways to integrate exercise into your life during the winter months.

5. Maintain a support system. Whether you need a friend to work out with or someone who will help you stay motivated, Greene emphasizes the value of getting support to help you commit to your new routine. Even if it is asking a family member to do the dishes so you can get a workout in, other people can greatly aid in making your resolution a reality.

6. Change up your routine. Not only can adding a mix to your workouts prevent injuries, it can also add some "spice" to your routine. Greene notes that the more fun you make exercise, the more likely you are to sustain it.

Changing up a routine also gives you the chance to target different areas of your body. While the typical recommendation for cardiovascular activity is 20 to 30 minutes at your target heart rate five to six days a week, it is important to engage in both aerobic and weight-training activities because research has also shown that strength training should be a part of every workout as well.

7. Realize that weight loss won't happen overnight. Greene suggests that a one- to two-pound weight loss per week is a realistic expectation, but it will take time to see significant results. Instead of only paying attention to the numbers on the scale, focus on how your clothes are feeling, how your resting heart rate is dropping and how you have more energy overall.

Greene also suggests watching TV or listening to music while exercising at home. The most important thing, she says, is simply making time to do it.