grind away at (someone or something)

1. To cause someone over time to feel dejected, unmotivated, hopeless, etc. This job really grinds away at you, until one day you wake up and wonder what the point of it all even is. I'm not surprised that his wife's death has driven him to despair—grief will grind away at you like that. If you're going to be an actor, you can't let rejection grind away you like this.

2. To frequently nag or disparage someone. Quit grinding away at me, will you? I'm doing the best I can! Of course the boss is going to grind away at you—you turned in your last three reports late! I'm sorry to grind away at you about it, but I need an answer soon.

3. To work hard on something; to dedicate oneself to some effort or task. I've been grinding away at the budget all morning, but I still can't figure out where that discrepancy came from. I did grind away at that term paper, and I still got a D! So frustrating! Wow, they really did grind away at fixing up the house, huh? It looks incredible!