How do you feel confident in the workplace?

I was a student for many years (5 years of undergrad, 2.5 years of grad school), and I became very comfortable with always being able to look at the syllabus and my grade and know what I needed to do and how well I was performing. Work isn’t like that. Like I think is normal, I get a performance review once a year. I find this unsettling, because even though I come in and do decent work, I still often feel like I’m doing something “wrong” and worry that I’m secretly on the cusp of being fired. Folks who have maybe been working for longer than I have, how do you feel and stay confident in your work?