If you’re like millions of other Americans, chances are, one of your New Year’s resolutions has to do with losing weight. Maybe last year you struggled to slim down for a special event; perhaps this year you’re committing to get back to your college best. Whatever your reasons, if you’re going to get serious about achieving your intention, the important first step is picking the right target.

Take a moment to think: Why that particular number? Are you picking it to improve your health? Or do you secretly believe when you reach that exact number you’ll find love, get promoted, or be happier? Have you been chasing it for years, and no matter how much you diet or exercise, you can’t reach it—or when you do, you can’t maintain it?

Like any SMART goals you set in life, your goal weight should be achievable and realistic. To help you figure that out, ask yourself these three key questions:

You may want to be size zero, but have you ever actually been a size zero? Hate to break it to you, but your dream weight might just not be right for you. Consider what your family members look like—are your genes programmed for a fit size 8? You don’t need to look like a cover model to be healthy, especially if it means surviving on air to get there. Think about the size that you were most comfortable at—one that didn’t require extreme dieting and misery to maintain.

The amount of time you’ve spent at a particular weight also makes a difference. If you’ve only gained a few pounds recently, they’ll drop off much more easily than if it’s taken years for the pounds to creep on. This doesn’t mean it’ll be impossible to lose them, just be prepared that it may take a bit more time. Acknowledge it and then commit to the challenge.

Yes, you can drop five pounds in five days by starving yourself, but you know those pounds will return. Are you really going to stick to that no-carb diet forever? Or completely forgo your favorite foods indefinitely? With small, less drastic changes, the weight may come off more slowly, but it’ll stay off. Be patient. Recognize that weight loss is a journey that takes time. Habits you’ve spent years creating may take years to change. Start slowly by choosing one at a time. You could cut back on your soda intake, switch your afternoon cookies for fruit, or simply cook more meals at home. Once you’ve mastered a new habit, pick another one, and slowly but surely, you’ll create a slimmer, healthier you who loves making healthy choices. And who will stick around for good, not just until the end of that 30-day diet. 

The body mass index (BMI) can be a useful tool to calculate your healthy weight range for your height. Ideally, your weight should fall between a BMI of 18.5 and 24.9. Try this quick calculation to get a sense for the guidelines.

Your lowest weight (pounds) =

18.5 x height (feet) x height (feet)
4.88

Your highest weight (pounds) =

24.9 x height (feet) x height (feet)
4.88

These healthy cut-offs give you a pretty big range of about 40 pounds (or 20 kilograms) that’s considered healthy for you. If the goal you’ve set for yourself falls below 18.5—it’s too low, and you need to ease up. If it’s above 24.9, but you have a lot to lose, that’s okay. Break your bigger goal down into smaller, achievable milestones, tackling one at a time. It makes it much less daunting. Initially, set your sights on losing just 5 to 10 percent of your body weight, divided into even smaller weekly goals. (These small losses are easier to sustain and still come with big health benefits!) Once you celebrate your first success, reevaluate, reset, and keep getting closer to that healthier BMI range, if need be.

Remember, obesity is an excess of body fat, and since muscle weighs more than fat, taking your body fat percentage into account is important, too. 200 pounds of mostly muscle is much healthier than 200 pounds of mostly fat, even though they both equate to the same BMI.

What the scale says naturally fluctuates by a few pounds from day to day because of changes in your body’s water stores. (That’s why it’s so important to weigh in at the same time every day, preferably first thing in the morning.) Rather than picking one magic number, aim for a reasonable range of up to 5 pounds. Once you’ve slimmed down, use these numbers as a guide to maintaining with regular weight checks—and ultimately, try to avoid having to set a weight-loss resolution ever again!

You can set a weight goal in the Fitbit app and track your progress using the Aria Air scale. Plus, keep an eye out for Personal Goal Setting, a new app feature launching later this month, which can help you set smarter (and more achievable!) goals.