Motivation, however, can be tricky, namely because there are various types of it, and employing the right one can mean the difference between success and failure. For simplicity’s sake, motivation is categorized into two different types—external and internal—and as you might guess, internal motivation tends to last longer.

External motivation comes from somebody or something outside of you. That might be a physician or spouse telling you that you need to lose weight or the diet industry nagging you to do something. Trouble is, this type of motivation can lead to pitfalls. “It becomes a ‘should’ or ‘have to,’ which can create a sense of guilt or shame,” Charland says.

Meanwhile, internal motivation comes from within—for instance, you’ve decided to embark on a goal because it’s important to you—and science has proven that it’s more sustainable over the long haul. Researchers asked 87 physically inactive adults to complete a ten-week program of high-intensity interval training or moderate-intensity exercise and evaluated the reasons why these individuals did what they were assigned. Those who had more intrinsic motivation during the program were more likely to adhere to that program, and that greater level of adherence meant they improved their fitness level and body fat percentage more, according to a study in Health Psychology. “When someone is intrinsically motivated, they’re doing an activity because they enjoy it and find pleasure in doing it, they think it’s fun, or they enjoy the challenges associated with doing the activity,” says Cecilie Thøgersen-Ntoumani, PhD, and lead study author from Curtin University in Australia. “When you enjoy doing an activity, you’re more likely to keep doing it, whereas you tend to avoid activities you don’t enjoy or find meaningful.”

That’s why if exercising is your goal, choosing a type of exercise you like is key to intrinsic motivation. Can’t think of any activity you enjoy? Thøgersen- Ntoumani encourages you to focus on the benefits of doing it.

Of course, while some people have an easier time identifying their internal drive, others may struggle—but not for reasons you might suspect. “It’s not because they don’t have it in them, but because they don’t understand what it is that motivates them,” Charland says. With a little work, though, everybody can tap into his or her inner motivation.