This bit in particular resonated with me, as someone who's had problems with nervousness giving piano recitals: I have a psychological approach to nerves as well. We have to consider the so-called importance of our little place in the world. This Beethoven performance is unlikely to be of any significance in three hundred years—and in three thousand years, not at all. It’s like standing on a different planet and look…
For example-- in a performance, you usually walk to the instrument, bow, sit down, adjust the bench, pause, consider the tempo... all to play the first few notes that establish the tempo of the piece.
So you would drill that entire entrance, as well as drilling from a sitting position and establishing the tempo.
What you'll probably find is that the variance in speed among these drills is well beyond what you desire for your performance. And the more you drill, the more control you have over the established tempo, which is probably the most important moment to not make a mistake. :)
This approach doesn't "solve" nerves. But it can slowly decouple them from the performance. E.g., you start freaking out because you never noticed how "weird" your thumbs look in this passage; nevertheless, muscle memory established a nice, solid tempo for your freakout instead of one thats 1.5x too fast... :)