persevere at (something)
To continue trying to improve at or succeed in doing something. Your writing isn't going to be amazing when you first start—you have to persevere at it. Even though I struggled at times, I persevered at my studies and ended up graduating with a 3.5 GPA.
persevere at something
to keep trying to do something. I will persevere at my studies and I'm sure I will succeed. Todd persevered at his job and got promoted in no time.