When we’ve done things a specific way, acted in a particular manner or simply held a specific point of view for any period of time, we tend to get comfortable. We decide that this is how things work for us, and develop our world view (and accompanying behaviors) around these models.
They might be models we’ve been taught or ones we’ve developed for ourselves, based on our own experiences. But they become ours, whether we think they’re good for us or not (and even when we know they’re not).