My Steps

NOTE: Tested on Nexus 5/6p. From user comments, it seems to works well on other devices too.
This application is designed to work without user intervention. It doesn't need to keep your phone awake and keeps counting your steps in the background so you don't have to manually enable/disable it.

It has several useful features such as:
- automatic disabling when power cable is detected (you can still enable it manually)
- switching between metric and US units
- manual enabling and disabling option, so you don't track unnecessary steps while driving in the car
- enter your weight daily to see your progress
- keep track of your BMI (body-mass index) as you loose weight
- view data as a chart
- see your progress on the lock screen without unlocking your phone
- place a widget on your home screen for an easy step tracking

It was reported that Samsung Galaxy S4 doesn't count steps while phone is asleep. After checking the documentation on this device, it turns out Samsung's step sensor gets disabled by Samsung for all programs utilizing their sensor while phone is in sleep mode. Apparently they use their own tracker S-Health, which has exclusive access to the sensor in the sleep mode. If you happen to have S4, it is recommended to use S-Health instead.