The idiomatic expression "to become a habit" means to develop or form a regular practice, behavior or routine. It is an action that someone does repeatedly over time until it becomes automatic and ingrained in their daily life.
Sentences with «to become a habit»
After 27 days or more of doing the same actions over and over again, the behaviors become a habit for students. (educationworld.com)
Use these foods as special treats so they don't become habit forming. (spotmagazine.net)
Since this perception quickly becomes habit - forming, you're almost always going too fast. (automobilemag.com)