Google Fit is the official app from Google to help improve your health in a very simple way: by informing you how much exercise you get on a daily basis. Users have to set themselves a number of daily and weekly goals; these could be anything from running for 45 minutes in the afternoon to cycling for 10 minutes on the way to work. Whatever the activity is, it is added to your activity graph. You'll also have to enter your height and weight to begin using Google Fit, as that way you can know if you're losing weight. Of course, even if you enter all your exercise plans on Google Fit, if you don't actually do them the app will remind you and you'll see their absence reflected in your graphic. Thus you'll have an extra incentive to exercise. Google Fit is a very useful app, like almost every other one developed by Google, and can also be connected to your Android Wear device or even consulted on its official website.
Requires Android 4.0 or higher