Trackr is an app that let's you track any type of activity.

It lets you create an activity you want to track, say you wanted to monitor your improvement of smoking, you could track how many cigarettes you smoked, the app then shows you a nice graph to visualize the data.
You can also create reminders that will show custom notifications for such activities.

Activities to track can be anything, it can track any good habit such as "working out", "drinking water" and so on or bad habits like smoking.