it could take anywhere from 18 to 254 days to form a habit and a day off didn’t hurt the chances of making that behavior a habit. However, the more often you do something, “the faster your brain will become accustomed to the behavior and make it automatic,” Dr. Brewer says. “Once the habit is established, it will become your default even if you’re not always in the same place or situation.” It is possible to form habits with things you repeat less often than daily, such as going to church weekly, he adds, but these may take longer to stick.