Plug away
Meaning: to work hard at something for a long time, to keep trying something, to keep working at something
Example: I'm still plugging away at my article. John kept pegging away at the trumpet until he became pretty good at it. I'm not very good at it, but I keep plugging away.
Example: I'm still plugging away at my article. John kept pegging away at the trumpet until he became pretty good at it. I'm not very good at it, but I keep plugging away.