It comes back to the mind. Our minds live in the past or future. It can't survive in the present.
Life is perfect as it is. The moment unfolding in front of you is moments that had happened in the past all the way back to 13.8 billion years ago. How can it not be perfect?
The work put in front of you is given to you by the Universe itself if you think about it. As long as you serve the best you can at that moment, then you're doing great!
It reminds of me The Four Agreement. The last agreement is "do the best you can". Your best changes moment to moment. As long as you put your energy out there and do you best, everything will be perfect as it is.
I find that understanding learning better helps with this. Effective learning requires knowing where you are at and what you need to do to get better given where you are at. In this sense trying to be the best is often the wrong goal.
Sounds simple but it was quite an issue for me. I was putting a tremendous pressure on myself and others, causing me anxiety and sadness.
Just doing the best I can and being happy. There's more life beyond work and perfection is just a falacy.