It’s okay to be mediocre if you’re consistent. What I mean by that is that you generally can’t judge the quality of your work by looking at a single day.
You’ll feel mediocre if you get up, take a shower, go to work, do some stuff that lots of other people can do while you’re at work, go home, watch Netflix, then go to bed. Nothing stands out about your day. That’s true of every individual day.
What this view misses is that consistently doing solid work every day for 30 years adds up to an elite level of output. Suppose you write a short script to do some task. You’re the only one that uses it. Then you add a few more features, and it slowly transforms from a script to an app. Month after month, you make changes here and there to fix bugs, take off the rough edges, and make it easier to use. You write up a short Readme file documenting the functionality. Over time, adding a few sentences here and a paragraph there, you end up with a 20-page manual covering everything in detail.
After ten years of slow, steady mediocrity, you have an app that provides value to many others. You didn’t need a twelve-hour hackathon to implement a complicated new algorithm.