Habitica, formerly known as HabitRPG is a habit tracker app for Android and iOS that also comes with an accompanying website to enable you to track your habits or keep ToDo Lists.
The concept is simple, you enter your habits, daily tasks and ToDos and then you have an easy way to keep track of what you do how much. The tasks are segmented in
- Habits (good and bad ones)
- Daily Tasks (also weekly or monthly possible)
- regular Todo Items
Also every task can have a difficulty. Drink Water for example I find trivial, but running 5k is medium/hard (at least in my world).