Try to smoke less by spending more time between cigarettes.
(For example, if you press the red button and then close the app or turn off your mobile phone and reopen the app after 40 minutes, the stopwatch continues from 40 minutes).
You can adjust the minutes that have passed since the last cigarette with the arrows.
There's also a counter that tracks cigarettes smoked (and you can set the cost per single cigarette and calculate the total amount spent).
The elapsed time relating to the previous cigarette also appears at the bottom.