The 21/90 Rule: It often takes about 21 days (3 weeks) for a new behavior to become routine, and about 90 days (3 months) for it to feel like part of a lifestyle. The 3-3-3 Rule: The first 3 days are ...

So why is it so hard to form new healthy habits? Behavioral scientists who study habit formation say that many of us try to create healthy habits the wrong way.