What is something you stopped caring about once you had more experience?

When I first started there were a lot of little things that appeared like big things. I was afraid I would not keep up. That I would make small mistakes. That I would not do enough. In retrospect, most of those concerns disappeared with experience.

Now I know I wasted probably more energy worrying than I ought to have. What is one thing you used to worry about that you do not worry about anymore?