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When it comes to fitness, like many endeavors, keeping track of what you plan to do, and when, has been shown to help people meet their goals. Apps can offer assistance in this area, whether they're counting your steps or calories, or charting your weekly strength-training goals.
They also offer something equally important, if less quantitative. “Perhaps the most striking effect is that people who used exercise apps had a lot more self-confidence in their ability to exercise, which itself leads to more exercise,” explains Leonid Litman, a psychology professor at Lander College, a division of Touro College in Queens, N.Y., whose research in this area links use of such apps with lower body mass index (BMI).

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What's more, he says, apps help remove barriers to exercise. These can be anything from insufficient motivation to lack of knowledge of how to exercise effectively. “Our research shows that the more barriers people have, the more likely they are to benefit from exercise apps."
If you're searching for a fitness app, know that many are free — though you may be required to look at the ads that come with them. To upgrade to an ad-free app, you usually have to pay a fee.
We love these four exercise apps — which are available for both iOS (iPhone) and Android — because they're easy to use and motivating: