be second nature

To be something that one can do with little conscious effort. I know this data entry process seems complex now, but it'll be second nature after you do it for a few weeks. You've just got to keep practicing and practicing until playing the notes is second nature to you. Don't worry, navigating these winding roads is second nature for me at this point.

be second ˈnature (to somebody)

be something that you do automatically, without thinking about it, because you have done it for so long or so often: It took a while to learn to drive, but now it’s second nature (to me).