A borrowed expression can make a second language feel briefly like a home.

Fluency in a new language is mostly effort, and then a phrase you picked up from someone lands correctly and the effort disappears for a second. Borrowed expressions carry the rhythm of the people you got them from, so using one is a little like standing where they stand. That momentary ease is not fluency, though it is a preview of it.

Collect the phrases you hear from real speakers rather than only from lessons, and use them even when they feel borrowed. Sounding briefly at home is a good reason to keep going on the days when the rest of it is hard.