Habitica - Habitica is a free habit building and productivity application.
Habit List - Create good habits and break bad ones with the app that keeps you focused.
When Did I…? - When Did I…?
Momentum - Agile goal and performance management
everyday.app - Every day, it gets a little easier. But you gotta do it every day, that's the hard part.
Autohabit - Simple iOS app to develop good habits