Even though it's named after a candy, Android 4.4 KitKat includes the means to get you fit and healthy. Sort of. Much like the iPhone 5s keeps track of your movements, KitKat has an internal step counter that logs the number of steps you take. You won't be able to access the step counter yourself, however; it's meant for the developers of fitness and navigation apps.
The step counter not only logs how many steps you've taken, but it'll also analyze stride and elevation to determine whether you're walking, running, or climbing up stairs. This should lead to more accurate fitness apps, which up to now have relied on a combination of the GPS and accelerometer to track your movements. Having the step counter built into the OS will also have the benefit of using less energy, so you'll be able to work out longer before your phone (or tablet?) needs to be juiced up again.
There's just one snag: Although the step counter functionality is native to KitKat, it still needs the hardware to support it. Google says it's working with its chipset partners to make the feature available across a wide variety of devices, but your current phone might not be able to take full advantage of the feature. Unless you have a Nexus 5 or Moto X--which already has special motion-tracking hardware--you'll probably have to wait until you upgrade your phone to notice a difference.