The hardest part of writing fiction for me is coming up with character names. They need to be setting-relevant, you're unlikely to want a modern day thriller's protagonist to be called Cellendrodil Ulthwaeven nor your high-fantasy hero named Joe McBland. This should help, it narrows your selection from the many possible and improbable names that you might choose or invent, but it only leads to further trouble. You want something memorable; your hero needs a name that somehow reflects the qualities that make him heroic. It should hint at his humble beginnings or his honourable birthright. It should display your Super-spy sex-vixen's sensual persona or your beat-Cop's earthy common sense. This is really hard.
We also need to capture a personal aesthetic; we have to like it. There are few choices a person can ever make that are more subjective. And so even when the ideas are flowing they are rejected one after another after another.
And of course, when the perfect name comes to you, out of the blue, you're in no position to write it down.