21 days
What this research suggests is that 21 days to form a habit is probably right, as long as all you want to do is drink a glass of water after breakfast. Anything harder is likely to take longer to become a really strong habit, and, in the case of some activities, much longer.
Making Habits, Breaking Habits: Why We Do Things, Why We Don’t, and How to Make Any Change Stick
Another feature I love in Toodledo is it’s Habit building feature.
