I've been drawing on paper for pretty much all of my life, but began doing digital art (sort of) nine years ago. With a mouse, because I had no way of getting a tablet at the time. I was mostly coloring my scanned drawings, but sometimes doodled with the mouse too. It was all seriously straining my wrist though 
(this is one such doodle from 2015)

I bought a tablet (to be specific, a cheap-ass second hand wacom lol) a year ago and it was surprisingly difficult for me to get used to it... it felt so completely different from drawing on paper. Ironically, my tablet sketches were worse than some of my old mouse drawings.
Took me around four months to even begin getting comfortable with it, and it took a whole year before I felt I could draw with a tablet the same as on paper. But I still prefer drawing on paper in some ways tbh (though I don't do it much recently). It was a long and arduous journey, but I'm glad I have not given up!
One of my first tablet drawings...
Part of my recent work (WIP)