Seth Godin
I would say this was one of the great books that came at a time when I needed it. I grew to faithfully stick to whatever I held onto. It eventually became an internal struggle as I didn't use my energy to stick with it, but rather out of guilt. Seth mentions that when you first stick with something, it's interesting and you're growing, until you meet a dip: where you get stuck, things get tough, or you face adversity. By recognizing this dip along the way, or even before starting, I could accept myself to quit, solely for myself, as I know where I'm heading. Not because of endless guilt.
With limited time or opportunity to experiment, we intentionally narrow our choices to those at the top. Scarcity makes being at the top worth something.
Where does the scarcity come from? It comes from the hurdles that the markets and our society set up. It comes from the fact that most competitors quit long before they've created something that makes it to the top.
Best as in: best for them, right now, based on what they believe and what they know. And in the world as in: their world, the world they have access to.
...if you're sold on being the best, but you've been frustrated in the route you're taking to get there, then you need to start doing some quitting.
If you're not going to put in the effort to be my best possible choice, why bother?
Quitting requires you to acknowledge that you're never going to be #1 in the world. At least not at this. So it's easier just to put it off, not admit it, settle for mediocre.
You can choose (in advance) to do whatever you need to do in order to get through the Dip, knowing it's going to be difficult; or you can give up before you get there.