With each new year comes the promise of fulfilling lofty goals, like achieving 7% body fat or sculpting a model-worthy, chiseled set of abs.

Yes, New Year's resolutions can be great motivators—but it's no secret that most people don't stick with resolutions for very long. Fresh new gear, like one of these stylish, high-tech smartwatches, can help you keep up with your weight-loss and muscle-building goals—but only if you use them the right way.

The single most important factor in translating that new Fitbit into weight loss? People must actively set daily or weekly goals for themselves, according to a new study published in the British Journal of Sports Medicine. Those who don't set goals while using the wearables, the study found, actually decrease their physical activity.

In the study, researchers followed more than 400 healthy adults (primarily office workers) over the course of six months, and tracked each participant's steps whenever they were wearing a fitness tracker. The researchers compared the results with the participant's goals (or lack thereof) and self-evaluation of their progress.

The results? People who set goals for themselves, like reaching a certain number of steps per day or doing two hours of moderate physical activity each week, saw a significant impact in their physical health. Those who didn't have a specific goal in mind actually saw their physical activity decline, even though some (mistakenly) thought their physical activity had increased.

So if you got a fancy new fitness tracker or smartwatch over the holidays—and want to crush your fat-burning resolutions this year—check out our primer on how to set fitness goals and crush them in seven easy steps.