For me, it is to tye the next fly better than the last. And to keep at it until I am satisfied with the results.
Perfection is a fools game. Success lies in doing your best, and quitting when you don't feel you are doing your best.
I get tired and quit for a while. Then a little later find myself trying again.
Something that has helped me a lot is #28 hooks, and 14/0 thread. Takes patience, and I love the challenge. It's just me and the materials. (And my mageyes...)
Can I do it? Well, I keep trying.
Besides, it's easy on my wore out back. Which is nobodies fault but my own.
But it's been fun getting here.
So one thing?
Perseverance.